Chapter 11 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, April 18, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Understanding Work and Kinetic Energy Learning Goal: To learn about the Work-Energy Theorem and its basic applications. In this problem, you will learn about the relationship between the work done on an object and the kinetic energy of that object. The kinetic energy of an object of mass moving at a speed is defined as . It seems reasonable to say that the speed of an object–and, therefore, its kinetic energy–can be changed by performing work on the object. In this problem, we will explore the mathematical relationship between the work done on an object and the change in the kinetic energy of that object. First, let us consider a sled of mass being pulled by a constant, horizontal force of magnitude along a rough, horizontal surface. The sled is speeding up. Part A How many forces are acting on the sled? ANSWER: Part B This question will be shown after you complete previous question(s). Part C K m v K = (1/2)mv2 m F one two three four This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G This question will be shown after you complete previous question(s). Part H This question will be shown after you complete previous question(s). Part I Typesetting math: 91% This question will be shown after you complete previous question(s). Part J This question will be shown after you complete previous question(s). Part K This question will be shown after you complete previous question(s). Work-Energy Theorem Reviewed Learning Goal: Review the work-energy theorem and apply it to a simple problem. If you push a particle of mass in the direction in which it is already moving, you expect the particle’s speed to increase. If you push with a constant force , then the particle will accelerate with acceleration (from Newton’s 2nd law). Part A Enter a one- or two-word answer that correctly completes the following statement. If the constant force is applied for a fixed interval of time , then the _____ of the particle will increase by an amount . You did not open hints for this part. ANSWER: M F a = F/M t at Typesetting math: 91% Part B Enter a one- or two-word answer that correctly completes the following statement. If the constant force is applied over a given distance , along the path of the particle, then the _____ of the particle will increase by . ANSWER: Part C If the initial kinetic energy of the particle is , and its final kinetic energy is , express in terms of and the work done on the particle. ANSWER: Part D In general, the work done by a force is written as . Now, consider whether the following statements are true or false: The dot product assures that the integrand is always nonnegative. The dot product indicates that only the component of the force perpendicular to the path contributes to the integral. The dot product indicates that only the component of the force parallel to the path contributes to the integral. Enter t for true or f for false for each statement. Separate your responses with commas (e.g., t,f,t). ANSWER: D FD Ki Kf Kf Ki W Kf = F W =  ( ) d f i F r r Typesetting math: 91% Part E Assume that the particle has initial speed . Find its final kinetic energy in terms of , , , and . You did not open hints for this part. ANSWER: Part F What is the final speed of the particle? Express your answer in terms of and . ANSWER: ± The Work Done in Pulling a Supertanker Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 2.20×106 , one at an angle 10.0 west of north, and the other at an angle 10.0 east of north, as they pull the tanker a distance 0.660 toward the north. Part A What is the total work done by the two tugboats on the supertanker? Express your answer in joules, to three significant figures. vi Kf vi M F D Kf = Kf M vf = N km Typesetting math: 91% You did not open hints for this part. ANSWER: Energy Required to Lift a Heavy Box As you are trying to move a heavy box of mass , you realize that it is too heavy for you to lift by yourself. There is no one around to help, so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. You pull up on the rope to lift the box. Use for the magnitude of the acceleration due to gravity and neglect friction forces. Part A Once you have pulled hard enough to start the box moving upward, what is the magnitude of the upward force you must apply to the rope to start raising the box with constant velocity? Express the magnitude of the force in terms of , the mass of the box. J m g F m Typesetting math: 91% You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Pulling a Block on an Incline with Friction A block of weight sits on an inclined plane as shown. A force of magnitude is applied to pull the block up the incline at constant speed. The coefficient of kinetic friction between the plane and the block is . Part A F = mg F μ Typesetting math: 91% What is the total work done on the block by the force of friction as the block moves a distance up the incline? Express the work done by friction in terms of any or all of the variables , , , , , and . You did not open hints for this part. ANSWER: Part B What is the total work done on the block by the applied force as the block moves a distance up the incline? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: Now the applied force is changed so that instead of pulling the block up the incline, the force pulls the block down the incline at a constant speed. Wfric L μ m g  L F Wfric = WF F L μ m g  L F WF = Typesetting math: 91% Part C What is the total work done on the block by the force of friction as the block moves a distance down the incline? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: Part D What is the total work done on the box by the appled force in this case? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: When Push Comes to Shove Two forces, of magnitudes = 75.0 and = 25.0 , act in opposite directions on a block, which sits atop a frictionless surface, as shown in the figure. Initially, the center of the block is at position = -1.00 . At some later time, the block has moved to the right, and its center is at a new position, = 1.00 . Wfric L μ m g  L F Wfric = WF μ m g  L F WF = F1 N F2 N xi cm xf cm Typesetting math: 91% Part A Find the work done on the block by the force of magnitude = 75.0 as the block moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: Part B Find the work done by the force of magnitude = 25.0 as the block moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: W1 F1 N xi cm xf cm W1 = J W2 F2 N xi cm xf cm Typesetting math: 91% Part C What is the net work done on the block by the two forces? Express your answer numerically, in joules. ANSWER: Part D Determine the change in the kinetic energy of the block as it moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: Work from a Constant Force Learning Goal: W2 = J Wnet Wnet = J Kf − Ki xi cm xf cm Kf − Ki = J Typesetting math: 91% To understand how to compute the work done by a constant force acting on a particle that moves in a straight line. In this problem, you will calculate the work done by a constant force. A force is considered constant if is independent of . This is the most frequently encountered situation in elementary Newtonian mechanics. Part A Consider a particle moving in a straight line from initial point B to final point A, acted upon by a constant force . The force (think of it as a field, having a magnitude and direction at every position ) is indicated by a series of identical vectors pointing to the left, parallel to the horizontal axis. The vectors are all identical only because the force is constant along the path. The magnitude of the force is , and the displacement vector from point B to point A is (of magnitude , making and angle (radians) with the positive x axis). Find , the work that the force performs on the particle as it moves from point B to point A. Express the work in terms of , , and . Remember to use radians, not degrees, for any angles that appear in your answer. You did not open hints for this part. ANSWER: Part B Now consider the same force acting on a particle that travels from point A to point B. The displacement vector now points in the opposite direction as it did in Part A. Find the work done by in this case. Express your answer in terms of , , and . F( r) r F r F L L  WBA F L F  WBA = F L WAB F Typesetting math: 91% L F  You did not open hints for this part. ANSWER: ± Vector Dot Product Let vectors , , and . Calculate the following: Part A You did not open hints for this part. ANSWER: WAB = A = (2, 1,−4) B = (−3, 0, 1) C = (−1,−1, 2) Typesetting math: 91% Part B What is the angle between and ? Express your answer using one significant figure. You did not open hints for this part. ANSWER: Part C ANSWER: Part D ANSWER: A B = AB A B AB = radians 2B 3C = Typesetting math: 91% Part E Which of the following can be computed? You did not open hints for this part. ANSWER: and are different vectors with lengths and respectively. Find the following: Part F Express your answer in terms of You did not open hints for this part. ANSWER: 2(B 3C) = A B C A (B C) A (B + C) 3 A V 1 V 2 V1 V2 V1 Typesetting math: 91% Part G If and are perpendicular, You did not open hints for this part. ANSWER: Part H If and are parallel, Express your answer in terms of and . You did not open hints for this part. ANSWER: ± Tactics Box 11.1 Calculating the Work Done by a Constant Force V = 1 V 1 V 1 V 2 V = 1 V 2 V 1 V 2 V1 V2 V = 1 V 2 Typesetting math: 91% Learning Goal: To practice Tactics Box 11.1 Calculating the Work Done by a Constant Force. Recall that the work done by a constant force at an angle to the displacement is . The vector magnitudes and are always positive, so the sign of is determined entirely by the angle between the force and the displacement. W F  d W = Fd cos  F d W  Typesetting math: 91% TACTICS BOX 11.1 Calculating the work done by a constant force Force and displacement Work Sign of Energy transfer Energy is transferred into the system. The particle speeds up. increases. No energy is transferred. Speed and are constant. Energy is transferred out of the system. The particle slows down. decreases. A box has weight of magnitude = 2.00 accelerates down a rough plane that is inclined at an angle = 30.0 above the horizontal, as shown at left. The normal force acting on the box has a magnitude = 1.732 , the coefficient of kinetic friction between the box and the plane is = 0.300, and the displacement of the box is 1.80 down the inclined plane.  W W 0 F(“r) + K < 90 F("r) cos  + 90 0 0 K > 90 F(“r) cos  − K 180 −F(“r) − FG N  n N μk d m Typesetting math: 91% Part A What is the work done on the box by gravity? Express your answers in joules to two significant figures. You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Wgrav Wgrav = J Typesetting math: 91% Work and Potential Energy on a Sliding Block with Friction A block of weight sits on a plane inclined at an angle as shown. The coefficient of kinetic friction between the plane and the block is . A force is applied to push the block up the incline at constant speed. Part A What is the work done on the block by the force of friction as the block moves a distance up the incline? Express your answer in terms of some or all of the following: , , , . You did not open hints for this part. ANSWER: w  μ F Wf L μ w  L Wf = Typesetting math: 91% Part B What is the work done by the applied force of magnitude ? Express your answer in terms of some or all of the following: , , , . ANSWER: Part C What is the change in the potential energy of the block, , after it has been pushed a distance up the incline? Express your answer in terms of some or all of the following: , , , . ANSWER: Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). W F μ w  L W = “U L μ w  L “U = Typesetting math: 91% Part F This question will be shown after you complete previous question(s). Where’s the Energy? Learning Goal: To understand how to apply the law of conservation of energy to situations with and without nonconservative forces acting. The law of conservation of energy states the following: In an isolated system the total energy remains constant. If the objects within the system interact through gravitational and elastic forces only, then the total mechanical energy is conserved. The mechanical energy of a system is defined as the sum of kinetic energy and potential energy . For such systems where no forces other than the gravitational and elastic forces do work, the law of conservation of energy can be written as , where the quantities with subscript “i” refer to the “initial” moment and those with subscript “f” refer to the final moment. A wise choice of initial and final moments, which is not always obvious, may significantly simplify the solution. The kinetic energy of an object that has mass \texttip{m}{m} and velocity \texttip{v}{v} is given by \large{K=\frac{1}{2}mv^2}. Potential energy, instead, has many forms. The two forms that you will be dealing with most often in this chapter are the gravitational and elastic potential energy. Gravitational potential energy is the energy possessed by elevated objects. For small heights, it can be found as U_{\rm g}=mgh, where \texttip{m}{m} is the mass of the object, \texttip{g}{g} is the acceleration due to gravity, and \texttip{h}{h} is the elevation of the object above the zero level. The zero level is the elevation at which the gravitational potential energy is assumed to be (you guessed it) zero. The choice of the zero level is dictated by convenience; typically (but not necessarily), it is selected to coincide with the lowest position of the object during the motion explored in the problem. Elastic potential energy is associated with stretched or compressed elastic objects such as springs. For a spring with a force constant \texttip{k}{k}, stretched or compressed a distance \texttip{x}{x}, the associated elastic potential energy is \large{U_{\rm e}=\frac{1}{2}kx^2}. When all three types of energy change, the law of conservation of energy for an object of mass \texttip{m}{m} can be written as K U Ki + Ui = Kf + Uf Typesetting math: 91% \large{\frac{1}{2}mv_{\rm i}^2+mgh_{\rm i}+\frac{1}{2}kx_{\rm i}^2=\frac{1}{2}mv_{\rm f \hspace{1 pt}}^2+mgh_{\rm f \hspace{1 pt}}+\frac{1}{2}kx_{\rm f \hspace{1 pt}}^2}. The gravitational force and the elastic force are two examples of conservative forces. What if nonconservative forces, such as friction, also act within the system? In that case, the total mechanical energy would change. The law of conservation of energy is then written as \large{\frac{1}{2}mv_{\rm i}^2+mgh_{\rm i}+\frac{1}{2}kx_{\rm i}^2+W_{\rm nc}=\frac{1}{2}mv_{\rm f \hspace{1 pt}}^2+mgh_{\rm f \hspace{1 pt}}+\frac{1}{2}kx_{\rm f \hspace{1 pt}}^2}, where \texttip{W_{\rm nc}}{W_nc} represents the work done by the nonconservative forces acting on the object between the initial and the final moments. The work \texttip{W_{\rm nc}}{W_nc} is usually negative; that is, the nonconservative forces tend to decrease, or dissipate, the mechanical energy of the system. In this problem, we will consider the following situation as depicted in the diagram : A block of mass \texttip{m}{m} slides at a speed \texttip{v}{v} along a horizontal, smooth table. It next slides down a smooth ramp, descending a height \texttip{h}{h}, and then slides along a horizontal rough floor, stopping eventually. Assume that the block slides slowly enough so that it does not lose contact with the supporting surfaces (table, ramp, or floor). You will analyze the motion of the block at different moments using the law of conservation of energy. Part A Which word in the statement of this problem allows you to assume that the table is frictionless? ANSWER: Part B straight smooth horizontal Typesetting math: 91% This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G This question will be shown after you complete previous question(s). Part H Typesetting math: 91% This question will be shown after you complete previous question(s). Part I This question will be shown after you complete previous question(s). Part J This question will be shown after you complete previous question(s). Part K This question will be shown after you complete previous question(s). Sliding In Socks Suppose that the coefficient of kinetic friction between Zak’s feet and the floor, while wearing socks, is 0.250. Knowing this, Zak decides to get a running start and then slide across the floor. Part A If Zak’s speed is 3.00 \rm m/s when he starts to slide, what distance \texttip{d}{d} will he slide before stopping? Express your answer in meters. ANSWER: Typesetting math: 91% Part B This question will be shown after you complete previous question(s). Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. \rm m Typesetting math: 91%

Chapter 11 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, April 18, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Understanding Work and Kinetic Energy Learning Goal: To learn about the Work-Energy Theorem and its basic applications. In this problem, you will learn about the relationship between the work done on an object and the kinetic energy of that object. The kinetic energy of an object of mass moving at a speed is defined as . It seems reasonable to say that the speed of an object–and, therefore, its kinetic energy–can be changed by performing work on the object. In this problem, we will explore the mathematical relationship between the work done on an object and the change in the kinetic energy of that object. First, let us consider a sled of mass being pulled by a constant, horizontal force of magnitude along a rough, horizontal surface. The sled is speeding up. Part A How many forces are acting on the sled? ANSWER: Part B This question will be shown after you complete previous question(s). Part C K m v K = (1/2)mv2 m F one two three four This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G This question will be shown after you complete previous question(s). Part H This question will be shown after you complete previous question(s). Part I Typesetting math: 91% This question will be shown after you complete previous question(s). Part J This question will be shown after you complete previous question(s). Part K This question will be shown after you complete previous question(s). Work-Energy Theorem Reviewed Learning Goal: Review the work-energy theorem and apply it to a simple problem. If you push a particle of mass in the direction in which it is already moving, you expect the particle’s speed to increase. If you push with a constant force , then the particle will accelerate with acceleration (from Newton’s 2nd law). Part A Enter a one- or two-word answer that correctly completes the following statement. If the constant force is applied for a fixed interval of time , then the _____ of the particle will increase by an amount . You did not open hints for this part. ANSWER: M F a = F/M t at Typesetting math: 91% Part B Enter a one- or two-word answer that correctly completes the following statement. If the constant force is applied over a given distance , along the path of the particle, then the _____ of the particle will increase by . ANSWER: Part C If the initial kinetic energy of the particle is , and its final kinetic energy is , express in terms of and the work done on the particle. ANSWER: Part D In general, the work done by a force is written as . Now, consider whether the following statements are true or false: The dot product assures that the integrand is always nonnegative. The dot product indicates that only the component of the force perpendicular to the path contributes to the integral. The dot product indicates that only the component of the force parallel to the path contributes to the integral. Enter t for true or f for false for each statement. Separate your responses with commas (e.g., t,f,t). ANSWER: D FD Ki Kf Kf Ki W Kf = F W =  ( ) d f i F r r Typesetting math: 91% Part E Assume that the particle has initial speed . Find its final kinetic energy in terms of , , , and . You did not open hints for this part. ANSWER: Part F What is the final speed of the particle? Express your answer in terms of and . ANSWER: ± The Work Done in Pulling a Supertanker Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 2.20×106 , one at an angle 10.0 west of north, and the other at an angle 10.0 east of north, as they pull the tanker a distance 0.660 toward the north. Part A What is the total work done by the two tugboats on the supertanker? Express your answer in joules, to three significant figures. vi Kf vi M F D Kf = Kf M vf = N km Typesetting math: 91% You did not open hints for this part. ANSWER: Energy Required to Lift a Heavy Box As you are trying to move a heavy box of mass , you realize that it is too heavy for you to lift by yourself. There is no one around to help, so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. You pull up on the rope to lift the box. Use for the magnitude of the acceleration due to gravity and neglect friction forces. Part A Once you have pulled hard enough to start the box moving upward, what is the magnitude of the upward force you must apply to the rope to start raising the box with constant velocity? Express the magnitude of the force in terms of , the mass of the box. J m g F m Typesetting math: 91% You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Pulling a Block on an Incline with Friction A block of weight sits on an inclined plane as shown. A force of magnitude is applied to pull the block up the incline at constant speed. The coefficient of kinetic friction between the plane and the block is . Part A F = mg F μ Typesetting math: 91% What is the total work done on the block by the force of friction as the block moves a distance up the incline? Express the work done by friction in terms of any or all of the variables , , , , , and . You did not open hints for this part. ANSWER: Part B What is the total work done on the block by the applied force as the block moves a distance up the incline? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: Now the applied force is changed so that instead of pulling the block up the incline, the force pulls the block down the incline at a constant speed. Wfric L μ m g  L F Wfric = WF F L μ m g  L F WF = Typesetting math: 91% Part C What is the total work done on the block by the force of friction as the block moves a distance down the incline? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: Part D What is the total work done on the box by the appled force in this case? Express your answer in terms of any or all of the variables , , , , , and . ANSWER: When Push Comes to Shove Two forces, of magnitudes = 75.0 and = 25.0 , act in opposite directions on a block, which sits atop a frictionless surface, as shown in the figure. Initially, the center of the block is at position = -1.00 . At some later time, the block has moved to the right, and its center is at a new position, = 1.00 . Wfric L μ m g  L F Wfric = WF μ m g  L F WF = F1 N F2 N xi cm xf cm Typesetting math: 91% Part A Find the work done on the block by the force of magnitude = 75.0 as the block moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: Part B Find the work done by the force of magnitude = 25.0 as the block moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: W1 F1 N xi cm xf cm W1 = J W2 F2 N xi cm xf cm Typesetting math: 91% Part C What is the net work done on the block by the two forces? Express your answer numerically, in joules. ANSWER: Part D Determine the change in the kinetic energy of the block as it moves from = -1.00 to = 1.00 . Express your answer numerically, in joules. You did not open hints for this part. ANSWER: Work from a Constant Force Learning Goal: W2 = J Wnet Wnet = J Kf − Ki xi cm xf cm Kf − Ki = J Typesetting math: 91% To understand how to compute the work done by a constant force acting on a particle that moves in a straight line. In this problem, you will calculate the work done by a constant force. A force is considered constant if is independent of . This is the most frequently encountered situation in elementary Newtonian mechanics. Part A Consider a particle moving in a straight line from initial point B to final point A, acted upon by a constant force . The force (think of it as a field, having a magnitude and direction at every position ) is indicated by a series of identical vectors pointing to the left, parallel to the horizontal axis. The vectors are all identical only because the force is constant along the path. The magnitude of the force is , and the displacement vector from point B to point A is (of magnitude , making and angle (radians) with the positive x axis). Find , the work that the force performs on the particle as it moves from point B to point A. Express the work in terms of , , and . Remember to use radians, not degrees, for any angles that appear in your answer. You did not open hints for this part. ANSWER: Part B Now consider the same force acting on a particle that travels from point A to point B. The displacement vector now points in the opposite direction as it did in Part A. Find the work done by in this case. Express your answer in terms of , , and . F( r) r F r F L L  WBA F L F  WBA = F L WAB F Typesetting math: 91% L F  You did not open hints for this part. ANSWER: ± Vector Dot Product Let vectors , , and . Calculate the following: Part A You did not open hints for this part. ANSWER: WAB = A = (2, 1,−4) B = (−3, 0, 1) C = (−1,−1, 2) Typesetting math: 91% Part B What is the angle between and ? Express your answer using one significant figure. You did not open hints for this part. ANSWER: Part C ANSWER: Part D ANSWER: A B = AB A B AB = radians 2B 3C = Typesetting math: 91% Part E Which of the following can be computed? You did not open hints for this part. ANSWER: and are different vectors with lengths and respectively. Find the following: Part F Express your answer in terms of You did not open hints for this part. ANSWER: 2(B 3C) = A B C A (B C) A (B + C) 3 A V 1 V 2 V1 V2 V1 Typesetting math: 91% Part G If and are perpendicular, You did not open hints for this part. ANSWER: Part H If and are parallel, Express your answer in terms of and . You did not open hints for this part. ANSWER: ± Tactics Box 11.1 Calculating the Work Done by a Constant Force V = 1 V 1 V 1 V 2 V = 1 V 2 V 1 V 2 V1 V2 V = 1 V 2 Typesetting math: 91% Learning Goal: To practice Tactics Box 11.1 Calculating the Work Done by a Constant Force. Recall that the work done by a constant force at an angle to the displacement is . The vector magnitudes and are always positive, so the sign of is determined entirely by the angle between the force and the displacement. W F  d W = Fd cos  F d W  Typesetting math: 91% TACTICS BOX 11.1 Calculating the work done by a constant force Force and displacement Work Sign of Energy transfer Energy is transferred into the system. The particle speeds up. increases. No energy is transferred. Speed and are constant. Energy is transferred out of the system. The particle slows down. decreases. A box has weight of magnitude = 2.00 accelerates down a rough plane that is inclined at an angle = 30.0 above the horizontal, as shown at left. The normal force acting on the box has a magnitude = 1.732 , the coefficient of kinetic friction between the box and the plane is = 0.300, and the displacement of the box is 1.80 down the inclined plane.  W W 0 F(“r) + K < 90 F("r) cos  + 90 0 0 K > 90 F(“r) cos  − K 180 −F(“r) − FG N  n N μk d m Typesetting math: 91% Part A What is the work done on the box by gravity? Express your answers in joules to two significant figures. You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Wgrav Wgrav = J Typesetting math: 91% Work and Potential Energy on a Sliding Block with Friction A block of weight sits on a plane inclined at an angle as shown. The coefficient of kinetic friction between the plane and the block is . A force is applied to push the block up the incline at constant speed. Part A What is the work done on the block by the force of friction as the block moves a distance up the incline? Express your answer in terms of some or all of the following: , , , . You did not open hints for this part. ANSWER: w  μ F Wf L μ w  L Wf = Typesetting math: 91% Part B What is the work done by the applied force of magnitude ? Express your answer in terms of some or all of the following: , , , . ANSWER: Part C What is the change in the potential energy of the block, , after it has been pushed a distance up the incline? Express your answer in terms of some or all of the following: , , , . ANSWER: Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). W F μ w  L W = “U L μ w  L “U = Typesetting math: 91% Part F This question will be shown after you complete previous question(s). Where’s the Energy? Learning Goal: To understand how to apply the law of conservation of energy to situations with and without nonconservative forces acting. The law of conservation of energy states the following: In an isolated system the total energy remains constant. If the objects within the system interact through gravitational and elastic forces only, then the total mechanical energy is conserved. The mechanical energy of a system is defined as the sum of kinetic energy and potential energy . For such systems where no forces other than the gravitational and elastic forces do work, the law of conservation of energy can be written as , where the quantities with subscript “i” refer to the “initial” moment and those with subscript “f” refer to the final moment. A wise choice of initial and final moments, which is not always obvious, may significantly simplify the solution. The kinetic energy of an object that has mass \texttip{m}{m} and velocity \texttip{v}{v} is given by \large{K=\frac{1}{2}mv^2}. Potential energy, instead, has many forms. The two forms that you will be dealing with most often in this chapter are the gravitational and elastic potential energy. Gravitational potential energy is the energy possessed by elevated objects. For small heights, it can be found as U_{\rm g}=mgh, where \texttip{m}{m} is the mass of the object, \texttip{g}{g} is the acceleration due to gravity, and \texttip{h}{h} is the elevation of the object above the zero level. The zero level is the elevation at which the gravitational potential energy is assumed to be (you guessed it) zero. The choice of the zero level is dictated by convenience; typically (but not necessarily), it is selected to coincide with the lowest position of the object during the motion explored in the problem. Elastic potential energy is associated with stretched or compressed elastic objects such as springs. For a spring with a force constant \texttip{k}{k}, stretched or compressed a distance \texttip{x}{x}, the associated elastic potential energy is \large{U_{\rm e}=\frac{1}{2}kx^2}. When all three types of energy change, the law of conservation of energy for an object of mass \texttip{m}{m} can be written as K U Ki + Ui = Kf + Uf Typesetting math: 91% \large{\frac{1}{2}mv_{\rm i}^2+mgh_{\rm i}+\frac{1}{2}kx_{\rm i}^2=\frac{1}{2}mv_{\rm f \hspace{1 pt}}^2+mgh_{\rm f \hspace{1 pt}}+\frac{1}{2}kx_{\rm f \hspace{1 pt}}^2}. The gravitational force and the elastic force are two examples of conservative forces. What if nonconservative forces, such as friction, also act within the system? In that case, the total mechanical energy would change. The law of conservation of energy is then written as \large{\frac{1}{2}mv_{\rm i}^2+mgh_{\rm i}+\frac{1}{2}kx_{\rm i}^2+W_{\rm nc}=\frac{1}{2}mv_{\rm f \hspace{1 pt}}^2+mgh_{\rm f \hspace{1 pt}}+\frac{1}{2}kx_{\rm f \hspace{1 pt}}^2}, where \texttip{W_{\rm nc}}{W_nc} represents the work done by the nonconservative forces acting on the object between the initial and the final moments. The work \texttip{W_{\rm nc}}{W_nc} is usually negative; that is, the nonconservative forces tend to decrease, or dissipate, the mechanical energy of the system. In this problem, we will consider the following situation as depicted in the diagram : A block of mass \texttip{m}{m} slides at a speed \texttip{v}{v} along a horizontal, smooth table. It next slides down a smooth ramp, descending a height \texttip{h}{h}, and then slides along a horizontal rough floor, stopping eventually. Assume that the block slides slowly enough so that it does not lose contact with the supporting surfaces (table, ramp, or floor). You will analyze the motion of the block at different moments using the law of conservation of energy. Part A Which word in the statement of this problem allows you to assume that the table is frictionless? ANSWER: Part B straight smooth horizontal Typesetting math: 91% This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G This question will be shown after you complete previous question(s). Part H Typesetting math: 91% This question will be shown after you complete previous question(s). Part I This question will be shown after you complete previous question(s). Part J This question will be shown after you complete previous question(s). Part K This question will be shown after you complete previous question(s). Sliding In Socks Suppose that the coefficient of kinetic friction between Zak’s feet and the floor, while wearing socks, is 0.250. Knowing this, Zak decides to get a running start and then slide across the floor. Part A If Zak’s speed is 3.00 \rm m/s when he starts to slide, what distance \texttip{d}{d} will he slide before stopping? Express your answer in meters. ANSWER: Typesetting math: 91% Part B This question will be shown after you complete previous question(s). Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. \rm m Typesetting math: 91%

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Assignment 10 Due: 11:59pm on Friday, April 18, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 12.3 Part A The figure shows three rotating disks, all of equal mass. Rank in order, from largest to smallest, their rotational kinetic energies to . Rank from largest to smallest. To rank items as equivalent, overlap them. ANSWER: Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 1 of 21 4/11/2014 1:13 PM Incorrect; Try Again Conceptual Question 12.6 You have two steel solid spheres. Sphere 2 has twice the radius of sphere 1. Part A By what factor does the moment of inertia of sphere 2 exceed the moment of inertia of sphere 1? ANSWER: Correct Problem 12.2 A high-speed drill reaches 2500 in 0.59 . Part A What is the drill’s angular acceleration? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B Through how many revolutions does it turn during this first 0.59 ? Express your answer to two significant figures and include the appropriate units. ANSWER: Constant Angular Acceleration in the Kitchen = 32 = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 2 of 21 4/11/2014 1:13 PM Dario, a prep cook at an Italian restaurant, spins a salad spinner and observes that it rotates 20.0 times in 5.00 seconds and then stops spinning it. The salad spinner rotates 6.00 more times before it comes to rest. Assume that the spinner slows down with constant angular acceleration. Part A What is the angular acceleration of the salad spinner as it slows down? Express your answer numerically in degrees per second per second. You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). ± A Spinning Electric Fan An electric fan is turned off, and its angular velocity decreases uniformly from 540 to 250 in a time interval of length 4.40 . Part A Find the angular acceleration in revolutions per second per second. You did not open hints for this part. ANSWER: Part B Find the number of revolutions made by the fan blades during the time that they are slowing down in Part A. = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 3 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part C How many more seconds are required for the fan to come to rest if the angular acceleration remains constant at the value calculated in Part A? You did not open hints for this part. ANSWER: Problem 12.8 A 100 ball and a 230 ball are connected by a 34- -long, massless, rigid rod. The balls rotate about their center of mass at 130 . Part A What is the speed of the 100 ball? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.10 A thin, 60.0 disk with a diameter of 9.00 rotates about an axis through its center with 0.200 of kinetic energy. Part A What is the speed of a point on the rim? = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 4 of 21 4/11/2014 1:13 PM Express your answer with the appropriate units. ANSWER: Problem 12.12 A drum major twirls a 95- -long, 470 baton about its center of mass at 150 . Part A What is the baton’s rotational kinetic energy? Express your answer to two significant figures and include the appropriate units. ANSWER: Net Torque on a Pulley The figure below shows two blocks suspended by a cord over a pulley. The mass of block B is twice the mass of block A, while the mass of the pulley is equal to the mass of block A. The blocks are let free to move and the cord moves on the pulley without slipping or stretching. There is no friction in the pulley axle, and the cord’s weight can be ignored. Part A Which of the following statements correctly describes the system shown in the figure? Check all that apply. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 5 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Problem 12.18 Part A In the figure , what is the magnitude of net torque about the axle? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the direction of net torque about the axle? ANSWER: The acceleration of the blocks is zero. The net torque on the pulley is zero. The angular acceleration of the pulley is nonzero. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 6 of 21 4/11/2014 1:13 PM Problem 12.22 An athlete at the gym holds a 3.5 steel ball in his hand. His arm is 78 long and has a mass of 3.6 . Assume the center of mass of the arm is at the geometrical center of the arm. Part A What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the magnitude of the torque about his shoulder if he holds his arm straight, but below horizontal? Express your answer to two significant figures and include the appropriate units. ANSWER: Parallel Axis Theorem The parallel axis theorem relates , the moment of inertia of an object about an axis passing through its center of mass, to , the moment of inertia of the same object about a parallel axis passing through point p. The mathematical statement of the theorem is , where is the perpendicular distance from the center of mass to the axis that passes through point p, and is the mass of the object. Part A Suppose a uniform slender rod has length and mass . The moment of inertia of the rod about about an axis that is perpendicular to the rod and that passes through its center of mass is given by . Find , the moment of inertia of the rod with respect to a parallel axis through one end of the rod. Express in terms of and . Use fractions rather than decimal numbers in your answer. Clockwise Counterclockwise = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 7 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part B Now consider a cube of mass with edges of length . The moment of inertia of the cube about an axis through its center of mass and perpendicular to one of its faces is given by . Find , the moment of inertia about an axis p through one of the edges of the cube Express in terms of and . Use fractions rather than decimal numbers in your answer. You did not open hints for this part. ANSWER: Problem 12.26 Starting from rest, a 12- -diameter compact disk takes 2.9 to reach its operating angular velocity of 2000 . Assume that the angular acceleration is constant. The disk’s moment of inertia is . Part A How much torque is applied to the disk? Express your answer to two significant figures and include the appropriate units. = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 8 of 21 4/11/2014 1:13 PM ANSWER: Part B How many revolutions does it make before reaching full speed? Express your answer using two significant figures. ANSWER: Problem 12.23 An object’s moment of inertia is 2.20 . Its angular velocity is increasing at the rate of 3.70 . Part A What is the total torque on the object? ANSWER: Problem 12.31 A 5.1 cat and a 2.5 bowl of tuna fish are at opposite ends of the 4.0- -long seesaw. = = rev Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 9 of 21 4/11/2014 1:13 PM Part A How far to the left of the pivot must a 3.8 cat stand to keep the seesaw balanced? Express your answer to two significant figures and include the appropriate units. ANSWER: Static Equilibrium of the Arm You are able to hold out your arm in an outstretched horizontal position because of the action of the deltoid muscle. Assume the humerus bone has a mass , length and its center of mass is a distance from the scapula. (For this problem ignore the rest of the arm.) The deltoid muscle attaches to the humerus a distance from the scapula. The deltoid muscle makes an angle of with the horizontal, as shown. Use throughout the problem. Part A Find the tension in the deltoid muscle. Express the tension in newtons, to the nearest integer. You did not open hints for this part. ANSWER: = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 10 of 21 4/11/2014 1:13 PM Part B Using the conditions for static equilibrium, find the magnitude of the vertical component of the force exerted by the scapula on the humerus (where the humerus attaches to the rest of the body). Express your answer in newtons, to the nearest integer. You did not open hints for this part. ANSWER: Part C Now find the magnitude of the horizontal component of the force exerted by the scapula on the humerus. Express your answer in newtons, to the nearest integer. ANSWER: ± Moments around a Rod A rod is bent into an L shape and attached at one point to a pivot. The rod sits on a frictionless table and the diagram is a view from above. This means that gravity can be ignored for this problem. There are three forces that are applied to the rod at different points and angles: , , and . Note that the dimensions of the bent rod are in centimeters in the figure, although the answers are requested in SI units (kilograms, meters, seconds). = N = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 11 of 21 4/11/2014 1:13 PM Part A If and , what does the magnitude of have to be for there to be rotational equilibrium? Answer numerically in newtons to two significant figures. You did not open hints for this part. ANSWER: Part B If the L-shaped rod has a moment of inertia , , , and again , how long a time would it take for the object to move through ( /4 radians)? Assume that as the object starts to move, each force moves with the object so as to retain its initial angle relative to the object. Express the time in seconds to two significant figures. You did not open hints for this part. ANSWER: Part C Now consider the situation in which and , but now a force with nonzero magnitude is acting on the rod. What does have to be to obtain equilibrium? Give a numerical answer, without trigonometric functions, in newtons, to two significant figures. You did not open hints for this part. ANSWER: = N = s = N Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 12 of 21 4/11/2014 1:13 PM Problem 12.32 A car tire is 55.0 in diameter. The car is traveling at a speed of 24.0 . Part A What is the tire’s rotation frequency, in rpm? Express your answer to three significant figures and include the appropriate units. ANSWER: Part B What is the speed of a point at the top edge of the tire? Express your answer to three significant figures and include the appropriate units. ANSWER: Part C What is the speed of a point at the bottom edge of the tire? Express your answer as an integer and include the appropriate units. ANSWER: Problem 12.33 A 460 , 8.00-cm-diameter solid cylinder rolls across the floor at 1.30 . Part A What is the can’s kinetic energy? Express your answer with the appropriate units. Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 13 of 21 4/11/2014 1:13 PM ANSWER: Problem 12.45 Part A What is the magnitude of the angular momentum of the 780 rotating bar in the figure ? ANSWER: Part B What is the direction of the angular momentum of the bar ? ANSWER: Problem 12.46 into the page out of the page Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 14 of 21 4/11/2014 1:13 PM Part A What is the magnitude of the angular momentum of the 2.20 , 4.60-cm-diameter rotating disk in the figure ? ANSWER: Part B What is its direction? ANSWER: Problem 12.60 A 3.0- -long ladder, as shown in the following figure, leans against a frictionless wall. The coefficient of static friction between the ladder and the floor is 0.46. x direction -x direction y direction -y direction z direction -z direction Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 15 of 21 4/11/2014 1:13 PM Part A What is the minimum angle the ladder can make with the floor without slipping? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.61 The 3.0- -long, 90 rigid beam in the following figure is supported at each end. An 70 student stands 2.0 from support 1. Part A How much upward force does the support 1 exert on the beam? Express your answer to two significant figures and include the appropriate units. ANSWER: = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 16 of 21 4/11/2014 1:13 PM Part B How much upward force does the support 2 exert on the beam? Express your answer to two significant figures and include the appropriate units. ANSWER: Enhanced EOC: Problem 12.63 A 44 , 5.5- -long beam is supported, but not attached to, the two posts in the figure . A 22 boy starts walking along the beam. You may want to review ( pages 330 – 334) . For help with math skills, you may want to review: The Vector Cross Product Part A How close can he get to the right end of the beam without it falling over? Express your answer to two significant figures and include the appropriate units. You did not open hints for this part. ANSWER: = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 17 of 21 4/11/2014 1:13 PM Problem 12.68 Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel’s energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.6 diameter and a mass of 270 . Its maximum angular velocity is 1500 . Part A A motor spins up the flywheel with a constant torque of 54 . How long does it take the flywheel to reach top speed? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B How much energy is stored in the flywheel? Express your answer to two significant figures and include the appropriate units. ANSWER: Part C The flywheel is disconnected from the motor and connected to a machine to which it will deliver energy. Half the energy stored in the flywheel is delivered in 2.2 . What is the average power delivered to the machine? Express your answer to two significant figures and include the appropriate units. ANSWER: = = = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 18 of 21 4/11/2014 1:13 PM Part D How much torque does the flywheel exert on the machine? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.71 The 3.30 , 40.0-cm-diameter disk in the figure is spinning at 350 . Part A How much friction force must the brake apply to the rim to bring the disk to a halt in 2.10 ? Express your answer with the appropriate units. ANSWER: Problem 12.74 A 5.0 , 60- -diameter cylinder rotates on an axle passing through one edge. The axle is parallel to the floor. The cylinder is held with the center of mass at the same height as the axle, then released. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 19 of 21 4/11/2014 1:13 PM Part A What is the magnitude of the cylinder’s initial angular acceleration? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the magnitude of the cylinder’s angular velocity when it is directly below the axle? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.82 A 45 figure skater is spinning on the toes of her skates at 0.90 . Her arms are outstretched as far as they will go. In this orientation, the skater can be modeled as a cylindrical torso (40 , 20 average diameter, 160 tall) plus two rod-like arms (2.5 each, 67 long) attached to the outside of the torso. The skater then raises her arms straight above her head, where she appears to be a 45 , 20- -diameter, 200- -tall cylinder. Part A What is her new rotation frequency, in revolutions per second? Express your answer to two significant figures and include the appropriate units. ANSWER: = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 20 of 21 4/11/2014 1:13 PM Score Summary: Your score on this assignment is 4.0%. You received 7.84 out of a possible total of 198 points. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?disp

Assignment 10 Due: 11:59pm on Friday, April 18, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 12.3 Part A The figure shows three rotating disks, all of equal mass. Rank in order, from largest to smallest, their rotational kinetic energies to . Rank from largest to smallest. To rank items as equivalent, overlap them. ANSWER: Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 1 of 21 4/11/2014 1:13 PM Incorrect; Try Again Conceptual Question 12.6 You have two steel solid spheres. Sphere 2 has twice the radius of sphere 1. Part A By what factor does the moment of inertia of sphere 2 exceed the moment of inertia of sphere 1? ANSWER: Correct Problem 12.2 A high-speed drill reaches 2500 in 0.59 . Part A What is the drill’s angular acceleration? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B Through how many revolutions does it turn during this first 0.59 ? Express your answer to two significant figures and include the appropriate units. ANSWER: Constant Angular Acceleration in the Kitchen = 32 = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 2 of 21 4/11/2014 1:13 PM Dario, a prep cook at an Italian restaurant, spins a salad spinner and observes that it rotates 20.0 times in 5.00 seconds and then stops spinning it. The salad spinner rotates 6.00 more times before it comes to rest. Assume that the spinner slows down with constant angular acceleration. Part A What is the angular acceleration of the salad spinner as it slows down? Express your answer numerically in degrees per second per second. You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). ± A Spinning Electric Fan An electric fan is turned off, and its angular velocity decreases uniformly from 540 to 250 in a time interval of length 4.40 . Part A Find the angular acceleration in revolutions per second per second. You did not open hints for this part. ANSWER: Part B Find the number of revolutions made by the fan blades during the time that they are slowing down in Part A. = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 3 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part C How many more seconds are required for the fan to come to rest if the angular acceleration remains constant at the value calculated in Part A? You did not open hints for this part. ANSWER: Problem 12.8 A 100 ball and a 230 ball are connected by a 34- -long, massless, rigid rod. The balls rotate about their center of mass at 130 . Part A What is the speed of the 100 ball? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.10 A thin, 60.0 disk with a diameter of 9.00 rotates about an axis through its center with 0.200 of kinetic energy. Part A What is the speed of a point on the rim? = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 4 of 21 4/11/2014 1:13 PM Express your answer with the appropriate units. ANSWER: Problem 12.12 A drum major twirls a 95- -long, 470 baton about its center of mass at 150 . Part A What is the baton’s rotational kinetic energy? Express your answer to two significant figures and include the appropriate units. ANSWER: Net Torque on a Pulley The figure below shows two blocks suspended by a cord over a pulley. The mass of block B is twice the mass of block A, while the mass of the pulley is equal to the mass of block A. The blocks are let free to move and the cord moves on the pulley without slipping or stretching. There is no friction in the pulley axle, and the cord’s weight can be ignored. Part A Which of the following statements correctly describes the system shown in the figure? Check all that apply. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 5 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Problem 12.18 Part A In the figure , what is the magnitude of net torque about the axle? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the direction of net torque about the axle? ANSWER: The acceleration of the blocks is zero. The net torque on the pulley is zero. The angular acceleration of the pulley is nonzero. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 6 of 21 4/11/2014 1:13 PM Problem 12.22 An athlete at the gym holds a 3.5 steel ball in his hand. His arm is 78 long and has a mass of 3.6 . Assume the center of mass of the arm is at the geometrical center of the arm. Part A What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the magnitude of the torque about his shoulder if he holds his arm straight, but below horizontal? Express your answer to two significant figures and include the appropriate units. ANSWER: Parallel Axis Theorem The parallel axis theorem relates , the moment of inertia of an object about an axis passing through its center of mass, to , the moment of inertia of the same object about a parallel axis passing through point p. The mathematical statement of the theorem is , where is the perpendicular distance from the center of mass to the axis that passes through point p, and is the mass of the object. Part A Suppose a uniform slender rod has length and mass . The moment of inertia of the rod about about an axis that is perpendicular to the rod and that passes through its center of mass is given by . Find , the moment of inertia of the rod with respect to a parallel axis through one end of the rod. Express in terms of and . Use fractions rather than decimal numbers in your answer. Clockwise Counterclockwise = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 7 of 21 4/11/2014 1:13 PM You did not open hints for this part. ANSWER: Part B Now consider a cube of mass with edges of length . The moment of inertia of the cube about an axis through its center of mass and perpendicular to one of its faces is given by . Find , the moment of inertia about an axis p through one of the edges of the cube Express in terms of and . Use fractions rather than decimal numbers in your answer. You did not open hints for this part. ANSWER: Problem 12.26 Starting from rest, a 12- -diameter compact disk takes 2.9 to reach its operating angular velocity of 2000 . Assume that the angular acceleration is constant. The disk’s moment of inertia is . Part A How much torque is applied to the disk? Express your answer to two significant figures and include the appropriate units. = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 8 of 21 4/11/2014 1:13 PM ANSWER: Part B How many revolutions does it make before reaching full speed? Express your answer using two significant figures. ANSWER: Problem 12.23 An object’s moment of inertia is 2.20 . Its angular velocity is increasing at the rate of 3.70 . Part A What is the total torque on the object? ANSWER: Problem 12.31 A 5.1 cat and a 2.5 bowl of tuna fish are at opposite ends of the 4.0- -long seesaw. = = rev Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 9 of 21 4/11/2014 1:13 PM Part A How far to the left of the pivot must a 3.8 cat stand to keep the seesaw balanced? Express your answer to two significant figures and include the appropriate units. ANSWER: Static Equilibrium of the Arm You are able to hold out your arm in an outstretched horizontal position because of the action of the deltoid muscle. Assume the humerus bone has a mass , length and its center of mass is a distance from the scapula. (For this problem ignore the rest of the arm.) The deltoid muscle attaches to the humerus a distance from the scapula. The deltoid muscle makes an angle of with the horizontal, as shown. Use throughout the problem. Part A Find the tension in the deltoid muscle. Express the tension in newtons, to the nearest integer. You did not open hints for this part. ANSWER: = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 10 of 21 4/11/2014 1:13 PM Part B Using the conditions for static equilibrium, find the magnitude of the vertical component of the force exerted by the scapula on the humerus (where the humerus attaches to the rest of the body). Express your answer in newtons, to the nearest integer. You did not open hints for this part. ANSWER: Part C Now find the magnitude of the horizontal component of the force exerted by the scapula on the humerus. Express your answer in newtons, to the nearest integer. ANSWER: ± Moments around a Rod A rod is bent into an L shape and attached at one point to a pivot. The rod sits on a frictionless table and the diagram is a view from above. This means that gravity can be ignored for this problem. There are three forces that are applied to the rod at different points and angles: , , and . Note that the dimensions of the bent rod are in centimeters in the figure, although the answers are requested in SI units (kilograms, meters, seconds). = N = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 11 of 21 4/11/2014 1:13 PM Part A If and , what does the magnitude of have to be for there to be rotational equilibrium? Answer numerically in newtons to two significant figures. You did not open hints for this part. ANSWER: Part B If the L-shaped rod has a moment of inertia , , , and again , how long a time would it take for the object to move through ( /4 radians)? Assume that as the object starts to move, each force moves with the object so as to retain its initial angle relative to the object. Express the time in seconds to two significant figures. You did not open hints for this part. ANSWER: Part C Now consider the situation in which and , but now a force with nonzero magnitude is acting on the rod. What does have to be to obtain equilibrium? Give a numerical answer, without trigonometric functions, in newtons, to two significant figures. You did not open hints for this part. ANSWER: = N = s = N Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 12 of 21 4/11/2014 1:13 PM Problem 12.32 A car tire is 55.0 in diameter. The car is traveling at a speed of 24.0 . Part A What is the tire’s rotation frequency, in rpm? Express your answer to three significant figures and include the appropriate units. ANSWER: Part B What is the speed of a point at the top edge of the tire? Express your answer to three significant figures and include the appropriate units. ANSWER: Part C What is the speed of a point at the bottom edge of the tire? Express your answer as an integer and include the appropriate units. ANSWER: Problem 12.33 A 460 , 8.00-cm-diameter solid cylinder rolls across the floor at 1.30 . Part A What is the can’s kinetic energy? Express your answer with the appropriate units. Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 13 of 21 4/11/2014 1:13 PM ANSWER: Problem 12.45 Part A What is the magnitude of the angular momentum of the 780 rotating bar in the figure ? ANSWER: Part B What is the direction of the angular momentum of the bar ? ANSWER: Problem 12.46 into the page out of the page Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 14 of 21 4/11/2014 1:13 PM Part A What is the magnitude of the angular momentum of the 2.20 , 4.60-cm-diameter rotating disk in the figure ? ANSWER: Part B What is its direction? ANSWER: Problem 12.60 A 3.0- -long ladder, as shown in the following figure, leans against a frictionless wall. The coefficient of static friction between the ladder and the floor is 0.46. x direction -x direction y direction -y direction z direction -z direction Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 15 of 21 4/11/2014 1:13 PM Part A What is the minimum angle the ladder can make with the floor without slipping? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.61 The 3.0- -long, 90 rigid beam in the following figure is supported at each end. An 70 student stands 2.0 from support 1. Part A How much upward force does the support 1 exert on the beam? Express your answer to two significant figures and include the appropriate units. ANSWER: = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 16 of 21 4/11/2014 1:13 PM Part B How much upward force does the support 2 exert on the beam? Express your answer to two significant figures and include the appropriate units. ANSWER: Enhanced EOC: Problem 12.63 A 44 , 5.5- -long beam is supported, but not attached to, the two posts in the figure . A 22 boy starts walking along the beam. You may want to review ( pages 330 – 334) . For help with math skills, you may want to review: The Vector Cross Product Part A How close can he get to the right end of the beam without it falling over? Express your answer to two significant figures and include the appropriate units. You did not open hints for this part. ANSWER: = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 17 of 21 4/11/2014 1:13 PM Problem 12.68 Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel’s energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.6 diameter and a mass of 270 . Its maximum angular velocity is 1500 . Part A A motor spins up the flywheel with a constant torque of 54 . How long does it take the flywheel to reach top speed? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B How much energy is stored in the flywheel? Express your answer to two significant figures and include the appropriate units. ANSWER: Part C The flywheel is disconnected from the motor and connected to a machine to which it will deliver energy. Half the energy stored in the flywheel is delivered in 2.2 . What is the average power delivered to the machine? Express your answer to two significant figures and include the appropriate units. ANSWER: = = = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 18 of 21 4/11/2014 1:13 PM Part D How much torque does the flywheel exert on the machine? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.71 The 3.30 , 40.0-cm-diameter disk in the figure is spinning at 350 . Part A How much friction force must the brake apply to the rim to bring the disk to a halt in 2.10 ? Express your answer with the appropriate units. ANSWER: Problem 12.74 A 5.0 , 60- -diameter cylinder rotates on an axle passing through one edge. The axle is parallel to the floor. The cylinder is held with the center of mass at the same height as the axle, then released. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 19 of 21 4/11/2014 1:13 PM Part A What is the magnitude of the cylinder’s initial angular acceleration? Express your answer to two significant figures and include the appropriate units. ANSWER: Part B What is the magnitude of the cylinder’s angular velocity when it is directly below the axle? Express your answer to two significant figures and include the appropriate units. ANSWER: Problem 12.82 A 45 figure skater is spinning on the toes of her skates at 0.90 . Her arms are outstretched as far as they will go. In this orientation, the skater can be modeled as a cylindrical torso (40 , 20 average diameter, 160 tall) plus two rod-like arms (2.5 each, 67 long) attached to the outside of the torso. The skater then raises her arms straight above her head, where she appears to be a 45 , 20- -diameter, 200- -tall cylinder. Part A What is her new rotation frequency, in revolutions per second? Express your answer to two significant figures and include the appropriate units. ANSWER: = = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?displayM… 20 of 21 4/11/2014 1:13 PM Score Summary: Your score on this assignment is 4.0%. You received 7.84 out of a possible total of 198 points. = Assignment 10 http://session.masteringphysics.com/myct/assignmentPrintView?disp

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Assignment 11 Due: 11:59pm on Wednesday, April 30, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 13.2 The gravitational force of a star on orbiting planet 1 is . Planet 2, which is twice as massive as planet 1 and orbits at twice the distance from the star, experiences gravitational force . Part A What is the ratio ? ANSWER: Correct Conceptual Question 13.3 A 1500 satellite and a 2200 satellite follow exactly the same orbit around the earth. Part A What is the ratio of the force on the first satellite to that on the second satellite? ANSWER: Correct F1 F2 F1 F2 = 2 F1 F2 kg kg F1 F2 = 0.682 F1 F2 Part B What is the ratio of the acceleration of the first satellite to that of the second satellite? ANSWER: Correct Problem 13.2 The centers of a 15.0 lead ball and a 90.0 lead ball are separated by 9.00 . Part A What gravitational force does each exert on the other? Express your answer with the appropriate units. ANSWER: Correct Part B What is the ratio of this gravitational force to the weight of the 90.0 ball? ANSWER: a1 a2 = 1 a1 a2 kg g cm 1.11×10−8 N g 1.26×10−8 Typesetting math: 100% Correct Problem 13.6 The space shuttle orbits 310 above the surface of the earth. Part A What is the gravitational force on a 7.5 sphere inside the space shuttle? Express your answer with the appropriate units. ANSWER: Correct ± A Satellite in Orbit A satellite used in a cellular telephone network has a mass of 2310 and is in a circular orbit at a height of 650 above the surface of the earth. Part A What is the gravitational force on the satellite? Take the gravitational constant to be = 6.67×10−11 , the mass of the earth to be = 5.97×1024 , and the radius of the Earth to be = 6.38×106 . Express your answer in newtons. Hint 1. How to approach the problem Use the equation for the law of gravitation to calculate the force on the satellite. Be careful about the units when performing the calculations. km kg Fe on s = 67.0 N kg km Fgrav G N m2/kg2 me kg re m Typesetting math: 100% Hint 2. Law of gravitation According to Newton’s law of gravitation, , where is the gravitational constant, and are the masses of the two objects, and is the distance between the centers of mass of the two objects. Hint 3. Calculate the distance between the centers of mass What is the distance from the center of mass of the satellite to the center of mass of the earth? Express your answer in meters. ANSWER: ANSWER: Correct Part B What fraction is this of the satellite’s weight at the surface of the earth? Take the free-fall acceleration at the surface of the earth to be = 9.80 . Hint 1. How to approach the problem All you need to do is to take the ratio of the gravitational force on the satellite to the weight of the satellite at ground level. There are two ways to do this, depending on how you define the force of gravity at the surface of the earth. ANSWER: F = Gm1m2/r2 G m1 m2 r r = 7.03×10r 6 m = 1.86×10Fgrav 4 N g m/s2 0.824 Typesetting math: 100% Correct Although it is easy to find the weight of the satellite using the constant acceleration due to gravity, it is instructional to consider the weight calculated using the law of gravitation: . Dividing the gravitational force on the satellite by , we find that the ratio of the forces due to the earth’s gravity is simply the square of the ratio of the earth’s radius to the sum of the earth’s radius and the height of the orbit of the satellite above the earth, . This will also be the fraction of the weight of, say, an astronaut in an orbit at the same altitude. Notice that an astronaut’s weight is never zero. When people speak of “weightlessness” in space, what they really mean is “free fall.” Problem 13.8 Part A What is the free-fall acceleration at the surface of the moon? Express your answer with the appropriate units. ANSWER: Correct Part B What is the free-fall acceleration at the surface of the Jupiter? Express your answer with the appropriate units. ANSWER: Correct w = G m/ me r2e Fgrav = Gmem/(re + h)2 w [re/(re + h)]2 gmoon = 1.62 m s2 gJupiter = 25.9 m s2 Typesetting math: 100% Enhanced EOC: Problem 13.14 A rocket is launched straight up from the earth’s surface at a speed of 1.90×104 . You may want to review ( pages 362 – 365) . For help with math skills, you may want to review: Mathematical Expressions Involving Squares Part A What is its speed when it is very far away from the earth? Express your answer with the appropriate units. Hint 1. How to approach the problem What is conserved in this problem? What is the rocket’s initial kinetic energy in terms of its unknown mass, ? What is the rocket’s initial gravitational potential energy in terms of its unknown mass, ? When the rocket is very far away from the Earth, what is its gravitational potential energy? Using conservation of energy, what is the rocket’s kinetic energy when it is very far away from the Earth? Therefore, what is the rocket’s velocity when it is very far away from the Earth? ANSWER: Correct Problem 13.13 Part A m/s m m 1.54×104 ms Typesetting math: 100% What is the escape speed from Venus? Express your answer with the appropriate units. ANSWER: Correct Problem 13.17 The asteroid belt circles the sun between the orbits of Mars and Jupiter. One asteroid has a period of 4.2 earth years. Part A What is the asteroid’s orbital radius? Express your answer with the appropriate units. ANSWER: Correct Part B What is the asteroid’s orbital speed? Express your answer with the appropriate units. ANSWER: vescape = 10.4 km s = 3.89×1011 R m = 1.85×104 v ms Typesetting math: 100% Correct Problem 13.32 Part A At what height above the earth is the acceleration due to gravity 15.0% of its value at the surface? Express your answer with the appropriate units. ANSWER: Correct Part B What is the speed of a satellite orbiting at that height? Express your answer with the appropriate units. ANSWER: Correct Problem 13.36 Two meteoroids are heading for earth. Their speeds as they cross the moon’s orbit are 2 . 1.01×107 m 4920 ms km/s Typesetting math: 100% Part A The first meteoroid is heading straight for earth. What is its speed of impact? Express your answer with the appropriate units. ANSWER: Correct Part B The second misses the earth by 5500 . What is its speed at its closest point? Express your answer with the appropriate units. ANSWER: Incorrect; Try Again Problem 14.2 An air-track glider attached to a spring oscillates between the 11.0 mark and the 67.0 mark on the track. The glider completes 11.0 oscillations in 32.0 . Part A What is the period of the oscillations? Express your answer with the appropriate units. v1 = 11.3 km s km v2 = cm cm s Typesetting math: 100% ANSWER: Correct Part B What is the frequency of the oscillations? Express your answer with the appropriate units. ANSWER: Correct Part C What is the angular frequency of the oscillations? Express your answer with the appropriate units. ANSWER: Correct Part D What is the amplitude? Express your answer with the appropriate units. 2.91 s 0.344 Hz 2.16 rad s Typesetting math: 100% ANSWER: Correct Part E What is the maximum speed of the glider? Express your answer with the appropriate units. ANSWER: Correct Good Vibes: Introduction to Oscillations Learning Goal: To learn the basic terminology and relationships among the main characteristics of simple harmonic motion. Motion that repeats itself over and over is called periodic motion. There are many examples of periodic motion: the earth revolving around the sun, an elastic ball bouncing up and down, or a block attached to a spring oscillating back and forth. The last example differs from the first two, in that it represents a special kind of periodic motion called simple harmonic motion. The conditions that lead to simple harmonic motion are as follows: There must be a position of stable equilibrium. There must be a restoring force acting on the oscillating object. The direction of this force must always point toward the equilibrium, and its magnitude must be directly proportional to the magnitude of the object’s displacement from its equilibrium position. Mathematically, the restoring force is given by , where is the displacement from equilibrium and is a constant that depends on the properties of the oscillating system. The resistive forces in the system must be reasonably small. In this problem, we will introduce some of the basic quantities that describe oscillations and the relationships among them. Consider a block of mass attached to a spring with force constant , as shown in the figure. The spring can be either stretched or compressed. The block slides on a frictionless horizontal surface, as shown. When the spring is relaxed, the block is located at . If the 28.0 cm 60.5 cms F  F = −kx x k m k x = 0 Typesetting math: 100% block is pulled to the right a distance and then released, will be the amplitude of the resulting oscillations. Assume that the mechanical energy of the block-spring system remains unchanged in the subsequent motion of the block. Part A After the block is released from , it will ANSWER: Correct As the block begins its motion to the left, it accelerates. Although the restoring force decreases as the block approaches equilibrium, it still pulls the block to the left, so by the time the equilibrium position is reached, the block has gained some speed. It will, therefore, pass the equilibrium position and keep moving, compressing the spring. The spring will now be pushing the block to the right, and the block will slow down, temporarily coming to rest at . After is reached, the block will begin its motion to the right, pushed by the spring. The block will pass the equilibrium position and continue until it reaches , completing one cycle of motion. The motion will then repeat; if, as we’ve assumed, there is no friction, the motion will repeat indefinitely. The time it takes the block to complete one cycle is called the period. Usually, the period is denoted and is measured in seconds. The frequency, denoted , is the number of cycles that are completed per unit of time: . In SI units, is measured in inverse seconds, or hertz ( ). A A x = A remain at rest. move to the left until it reaches equilibrium and stop there. move to the left until it reaches and stop there. move to the left until it reaches and then begin to move to the right. x = −A x = −A x = −A x = −A x = A T f f = 1/T f Hz Typesetting math: 100% Part B If the period is doubled, the frequency is ANSWER: Correct Part C An oscillating object takes 0.10 to complete one cycle; that is, its period is 0.10 . What is its frequency ? Express your answer in hertz. ANSWER: Correct unchanged. doubled. halved. s s f f = 10 Hz Typesetting math: 100% Part D If the frequency is 40 , what is the period ? Express your answer in seconds. ANSWER: Correct The following questions refer to the figure that graphically depicts the oscillations of the block on the spring. Note that the vertical axis represents the x coordinate of the oscillating object, and the horizontal axis represents time. Part E Which points on the x axis are located a distance from the equilibrium position? ANSWER: Hz T T = 0.025 s A Typesetting math: 100% Correct Part F Suppose that the period is . Which of the following points on the t axis are separated by the time interval ? ANSWER: Correct Now assume for the remaining Parts G – J, that the x coordinate of point R is 0.12 and the t coordinate of point K is 0.0050 . Part G What is the period ? Express your answer in seconds. Hint 1. How to approach the problem In moving from the point to the point K, what fraction of a full wavelength is covered? Call that fraction . Then you can set . Dividing by the fraction will give the R only Q only both R and Q T T K and L K and M K and P L and N M and P m s T t = 0 a aT = 0.005 s a Typesetting math: 100% period . ANSWER: Correct Part H How much time does the block take to travel from the point of maximum displacement to the opposite point of maximum displacement? Express your answer in seconds. ANSWER: Correct Part I What distance does the object cover during one period of oscillation? Express your answer in meters. ANSWER: Correct Part J What distance does the object cover between the moments labeled K and N on the graph? T T = 0.02 s t t = 0.01 s d d = 0.48 m d Typesetting math: 100% Express your answer in meters. ANSWER: Correct Problem 14.4 Part A What is the amplitude of the oscillation shown in the figure? Express your answer to three significant figures and include the appropriate units. ANSWER: Correct d = 0.36 m A = 20.0 cm Typesetting math: 100% Part B What is the frequency of this oscillation? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C What is the phase constant? Express your answer to two significant figures and include the appropriate units. ANSWER: Incorrect; Try Again Problem 14.10 An air-track glider attached to a spring oscillates with a period of 1.50 . At the glider is 4.60 left of the equilibrium position and moving to the right at 33.4 . Part A What is the phase constant? Express your answer to three significant figures and include the appropriate units. ANSWER: f = 0.25 Hz 0 = s t = 0 s cm cm/s Typesetting math: 100% Incorrect; Try Again Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Problem 14.12 A 140 air-track glider is attached to a spring. The glider is pushed in 12.2 and released. A student with a stopwatch finds that 14.0 oscillations take 19.0 . Part A What is the spring constant? Express your answer with the appropriate units. ANSWER: 0 = g cm s Typesetting math: 100% Correct Problem 14.14 The position of a 50 g oscillating mass is given by , where is in s. If necessary, round your answers to three significant figures. Determine: Part A The amplitude. Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Part B The period. Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Part C 3.00 Nm x(t) = (2.0 cm)cos(10t − /4) t 2.00 cm 0.628 s Typesetting math: 100% The spring constant. Express your answer to three significant figures and include the appropriate units. ANSWER: Part D The phase constant. Express your answer to three significant figures and include the appropriate units. ANSWER: Incorrect; Try Again Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G Typesetting math: 100% This question will be shown after you complete previous question(s). Part H This question will be shown after you complete previous question(s). Part I This question will be shown after you complete previous question(s). Enhanced EOC: Problem 14.17 A spring with spring constant 16 hangs from the ceiling. A ball is attached to the spring and allowed to come to rest. It is then pulled down 4.0 and released. The ball makes 35 oscillations in 18 seconds. You may want to review ( pages 389 – 391) . For help with math skills, you may want to review: Differentiation of Trigonometric Functions Part A What is its the mass of the ball? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the period of oscillation? What is the angular frequency of the oscillations? How is the angular frequency related to the mass and spring constant? What is the mass? N/m cm s Typesetting math: 100% ANSWER: Correct Part B What is its maximum speed? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the amplitude of the oscillations? How is the maximum speed related to the amplitude of the oscillations and the angular frequency? ANSWER: Correct Changing the Period of a Pendulum A simple pendulum consisting of a bob of mass attached to a string of length swings with a period . Part A If the bob’s mass is doubled, approximately what will the pendulum’s new period be? Hint 1. Period of a simple pendulum The period of a simple pendulum of length is given by m = 110 g vmax = 49 cms m L T Typesetting math: 10T0% L , where is the acceleration due to gravity. ANSWER: Correct Part B If the pendulum is brought on the moon where the gravitational acceleration is about , approximately what will its period now be? Hint 1. How to approach the problem Recall the formula of the period of a simple pendulum. Since the gravitational acceleration appears in the denominator, the period must increase when the gravitational acceleration decreases. ANSWER: T = 2 Lg −−  g T/2 T &2T 2T g/6 T/6 T/&6 &6T 6T Typesetting math: 100% Correct Part C If the pendulum is taken into the orbiting space station what will happen to the bob? Hint 1. How to approach the problem Recall that the oscillations of a simple pendulum occur when a pendulum bob is raised above its equilibrium position and let go, causing the pendulum bob to fall. The gravitational force acts to bring the bob back to its equilibrium position. In the space station, the earth’s gravity acts on both the station and everything inside it, giving them the same acceleration. These objects are said to be in free fall. ANSWER: Correct In the space station, where all objects undergo the same acceleration due to the earth’s gravity, the tension in the string is zero and the bob does not fall relative to the point to which the string is attached. Problem 14.20 A 175 ball is tied to a string. It is pulled to an angle of 8.0 and released to swing as a pendulum. A student with a stopwatch finds that 15 oscillations take 13 . Part A How long is the string? Express your answer to two significant figures and include the appropriate units. It will continue to oscillate in a vertical plane with the same period. It will no longer oscillate because there is no gravity in space. It will no longer oscillate because both the pendulum and the point to which it is attached are in free fall. It will oscillate much faster with a period that approaches zero. g ( s Typesetting math: 100% ANSWER: Correct Problem 14.22 Part A What is the length of a pendulum whose period on the moon matches the period of a 2.1- -long pendulum on the earth? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 14.42 An ultrasonic transducer, of the type used in medical ultrasound imaging, is a very thin disk ( = 0.17 ) driven back and forth in SHM at by an electromagnetic coil. Part A The maximum restoring force that can be applied to the disk without breaking it is 4.4×104 . What is the maximum oscillation amplitude that won’t rupture the disk? Express your answer to two significant figures and include the appropriate units. ANSWER: L = 19 cm m lmoon = 0.35 m m g 1.0 MHz N amax = 6.6 μm Typesetting math: 100% Correct Part B What is the disk’s maximum speed at this amplitude? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 81.4%. You received 117.25 out of a possible total of 144 points. vmax = 41 ms

Assignment 11 Due: 11:59pm on Wednesday, April 30, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 13.2 The gravitational force of a star on orbiting planet 1 is . Planet 2, which is twice as massive as planet 1 and orbits at twice the distance from the star, experiences gravitational force . Part A What is the ratio ? ANSWER: Correct Conceptual Question 13.3 A 1500 satellite and a 2200 satellite follow exactly the same orbit around the earth. Part A What is the ratio of the force on the first satellite to that on the second satellite? ANSWER: Correct F1 F2 F1 F2 = 2 F1 F2 kg kg F1 F2 = 0.682 F1 F2 Part B What is the ratio of the acceleration of the first satellite to that of the second satellite? ANSWER: Correct Problem 13.2 The centers of a 15.0 lead ball and a 90.0 lead ball are separated by 9.00 . Part A What gravitational force does each exert on the other? Express your answer with the appropriate units. ANSWER: Correct Part B What is the ratio of this gravitational force to the weight of the 90.0 ball? ANSWER: a1 a2 = 1 a1 a2 kg g cm 1.11×10−8 N g 1.26×10−8 Typesetting math: 100% Correct Problem 13.6 The space shuttle orbits 310 above the surface of the earth. Part A What is the gravitational force on a 7.5 sphere inside the space shuttle? Express your answer with the appropriate units. ANSWER: Correct ± A Satellite in Orbit A satellite used in a cellular telephone network has a mass of 2310 and is in a circular orbit at a height of 650 above the surface of the earth. Part A What is the gravitational force on the satellite? Take the gravitational constant to be = 6.67×10−11 , the mass of the earth to be = 5.97×1024 , and the radius of the Earth to be = 6.38×106 . Express your answer in newtons. Hint 1. How to approach the problem Use the equation for the law of gravitation to calculate the force on the satellite. Be careful about the units when performing the calculations. km kg Fe on s = 67.0 N kg km Fgrav G N m2/kg2 me kg re m Typesetting math: 100% Hint 2. Law of gravitation According to Newton’s law of gravitation, , where is the gravitational constant, and are the masses of the two objects, and is the distance between the centers of mass of the two objects. Hint 3. Calculate the distance between the centers of mass What is the distance from the center of mass of the satellite to the center of mass of the earth? Express your answer in meters. ANSWER: ANSWER: Correct Part B What fraction is this of the satellite’s weight at the surface of the earth? Take the free-fall acceleration at the surface of the earth to be = 9.80 . Hint 1. How to approach the problem All you need to do is to take the ratio of the gravitational force on the satellite to the weight of the satellite at ground level. There are two ways to do this, depending on how you define the force of gravity at the surface of the earth. ANSWER: F = Gm1m2/r2 G m1 m2 r r = 7.03×10r 6 m = 1.86×10Fgrav 4 N g m/s2 0.824 Typesetting math: 100% Correct Although it is easy to find the weight of the satellite using the constant acceleration due to gravity, it is instructional to consider the weight calculated using the law of gravitation: . Dividing the gravitational force on the satellite by , we find that the ratio of the forces due to the earth’s gravity is simply the square of the ratio of the earth’s radius to the sum of the earth’s radius and the height of the orbit of the satellite above the earth, . This will also be the fraction of the weight of, say, an astronaut in an orbit at the same altitude. Notice that an astronaut’s weight is never zero. When people speak of “weightlessness” in space, what they really mean is “free fall.” Problem 13.8 Part A What is the free-fall acceleration at the surface of the moon? Express your answer with the appropriate units. ANSWER: Correct Part B What is the free-fall acceleration at the surface of the Jupiter? Express your answer with the appropriate units. ANSWER: Correct w = G m/ me r2e Fgrav = Gmem/(re + h)2 w [re/(re + h)]2 gmoon = 1.62 m s2 gJupiter = 25.9 m s2 Typesetting math: 100% Enhanced EOC: Problem 13.14 A rocket is launched straight up from the earth’s surface at a speed of 1.90×104 . You may want to review ( pages 362 – 365) . For help with math skills, you may want to review: Mathematical Expressions Involving Squares Part A What is its speed when it is very far away from the earth? Express your answer with the appropriate units. Hint 1. How to approach the problem What is conserved in this problem? What is the rocket’s initial kinetic energy in terms of its unknown mass, ? What is the rocket’s initial gravitational potential energy in terms of its unknown mass, ? When the rocket is very far away from the Earth, what is its gravitational potential energy? Using conservation of energy, what is the rocket’s kinetic energy when it is very far away from the Earth? Therefore, what is the rocket’s velocity when it is very far away from the Earth? ANSWER: Correct Problem 13.13 Part A m/s m m 1.54×104 ms Typesetting math: 100% What is the escape speed from Venus? Express your answer with the appropriate units. ANSWER: Correct Problem 13.17 The asteroid belt circles the sun between the orbits of Mars and Jupiter. One asteroid has a period of 4.2 earth years. Part A What is the asteroid’s orbital radius? Express your answer with the appropriate units. ANSWER: Correct Part B What is the asteroid’s orbital speed? Express your answer with the appropriate units. ANSWER: vescape = 10.4 km s = 3.89×1011 R m = 1.85×104 v ms Typesetting math: 100% Correct Problem 13.32 Part A At what height above the earth is the acceleration due to gravity 15.0% of its value at the surface? Express your answer with the appropriate units. ANSWER: Correct Part B What is the speed of a satellite orbiting at that height? Express your answer with the appropriate units. ANSWER: Correct Problem 13.36 Two meteoroids are heading for earth. Their speeds as they cross the moon’s orbit are 2 . 1.01×107 m 4920 ms km/s Typesetting math: 100% Part A The first meteoroid is heading straight for earth. What is its speed of impact? Express your answer with the appropriate units. ANSWER: Correct Part B The second misses the earth by 5500 . What is its speed at its closest point? Express your answer with the appropriate units. ANSWER: Incorrect; Try Again Problem 14.2 An air-track glider attached to a spring oscillates between the 11.0 mark and the 67.0 mark on the track. The glider completes 11.0 oscillations in 32.0 . Part A What is the period of the oscillations? Express your answer with the appropriate units. v1 = 11.3 km s km v2 = cm cm s Typesetting math: 100% ANSWER: Correct Part B What is the frequency of the oscillations? Express your answer with the appropriate units. ANSWER: Correct Part C What is the angular frequency of the oscillations? Express your answer with the appropriate units. ANSWER: Correct Part D What is the amplitude? Express your answer with the appropriate units. 2.91 s 0.344 Hz 2.16 rad s Typesetting math: 100% ANSWER: Correct Part E What is the maximum speed of the glider? Express your answer with the appropriate units. ANSWER: Correct Good Vibes: Introduction to Oscillations Learning Goal: To learn the basic terminology and relationships among the main characteristics of simple harmonic motion. Motion that repeats itself over and over is called periodic motion. There are many examples of periodic motion: the earth revolving around the sun, an elastic ball bouncing up and down, or a block attached to a spring oscillating back and forth. The last example differs from the first two, in that it represents a special kind of periodic motion called simple harmonic motion. The conditions that lead to simple harmonic motion are as follows: There must be a position of stable equilibrium. There must be a restoring force acting on the oscillating object. The direction of this force must always point toward the equilibrium, and its magnitude must be directly proportional to the magnitude of the object’s displacement from its equilibrium position. Mathematically, the restoring force is given by , where is the displacement from equilibrium and is a constant that depends on the properties of the oscillating system. The resistive forces in the system must be reasonably small. In this problem, we will introduce some of the basic quantities that describe oscillations and the relationships among them. Consider a block of mass attached to a spring with force constant , as shown in the figure. The spring can be either stretched or compressed. The block slides on a frictionless horizontal surface, as shown. When the spring is relaxed, the block is located at . If the 28.0 cm 60.5 cms F  F = −kx x k m k x = 0 Typesetting math: 100% block is pulled to the right a distance and then released, will be the amplitude of the resulting oscillations. Assume that the mechanical energy of the block-spring system remains unchanged in the subsequent motion of the block. Part A After the block is released from , it will ANSWER: Correct As the block begins its motion to the left, it accelerates. Although the restoring force decreases as the block approaches equilibrium, it still pulls the block to the left, so by the time the equilibrium position is reached, the block has gained some speed. It will, therefore, pass the equilibrium position and keep moving, compressing the spring. The spring will now be pushing the block to the right, and the block will slow down, temporarily coming to rest at . After is reached, the block will begin its motion to the right, pushed by the spring. The block will pass the equilibrium position and continue until it reaches , completing one cycle of motion. The motion will then repeat; if, as we’ve assumed, there is no friction, the motion will repeat indefinitely. The time it takes the block to complete one cycle is called the period. Usually, the period is denoted and is measured in seconds. The frequency, denoted , is the number of cycles that are completed per unit of time: . In SI units, is measured in inverse seconds, or hertz ( ). A A x = A remain at rest. move to the left until it reaches equilibrium and stop there. move to the left until it reaches and stop there. move to the left until it reaches and then begin to move to the right. x = −A x = −A x = −A x = −A x = A T f f = 1/T f Hz Typesetting math: 100% Part B If the period is doubled, the frequency is ANSWER: Correct Part C An oscillating object takes 0.10 to complete one cycle; that is, its period is 0.10 . What is its frequency ? Express your answer in hertz. ANSWER: Correct unchanged. doubled. halved. s s f f = 10 Hz Typesetting math: 100% Part D If the frequency is 40 , what is the period ? Express your answer in seconds. ANSWER: Correct The following questions refer to the figure that graphically depicts the oscillations of the block on the spring. Note that the vertical axis represents the x coordinate of the oscillating object, and the horizontal axis represents time. Part E Which points on the x axis are located a distance from the equilibrium position? ANSWER: Hz T T = 0.025 s A Typesetting math: 100% Correct Part F Suppose that the period is . Which of the following points on the t axis are separated by the time interval ? ANSWER: Correct Now assume for the remaining Parts G – J, that the x coordinate of point R is 0.12 and the t coordinate of point K is 0.0050 . Part G What is the period ? Express your answer in seconds. Hint 1. How to approach the problem In moving from the point to the point K, what fraction of a full wavelength is covered? Call that fraction . Then you can set . Dividing by the fraction will give the R only Q only both R and Q T T K and L K and M K and P L and N M and P m s T t = 0 a aT = 0.005 s a Typesetting math: 100% period . ANSWER: Correct Part H How much time does the block take to travel from the point of maximum displacement to the opposite point of maximum displacement? Express your answer in seconds. ANSWER: Correct Part I What distance does the object cover during one period of oscillation? Express your answer in meters. ANSWER: Correct Part J What distance does the object cover between the moments labeled K and N on the graph? T T = 0.02 s t t = 0.01 s d d = 0.48 m d Typesetting math: 100% Express your answer in meters. ANSWER: Correct Problem 14.4 Part A What is the amplitude of the oscillation shown in the figure? Express your answer to three significant figures and include the appropriate units. ANSWER: Correct d = 0.36 m A = 20.0 cm Typesetting math: 100% Part B What is the frequency of this oscillation? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C What is the phase constant? Express your answer to two significant figures and include the appropriate units. ANSWER: Incorrect; Try Again Problem 14.10 An air-track glider attached to a spring oscillates with a period of 1.50 . At the glider is 4.60 left of the equilibrium position and moving to the right at 33.4 . Part A What is the phase constant? Express your answer to three significant figures and include the appropriate units. ANSWER: f = 0.25 Hz 0 = s t = 0 s cm cm/s Typesetting math: 100% Incorrect; Try Again Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Problem 14.12 A 140 air-track glider is attached to a spring. The glider is pushed in 12.2 and released. A student with a stopwatch finds that 14.0 oscillations take 19.0 . Part A What is the spring constant? Express your answer with the appropriate units. ANSWER: 0 = g cm s Typesetting math: 100% Correct Problem 14.14 The position of a 50 g oscillating mass is given by , where is in s. If necessary, round your answers to three significant figures. Determine: Part A The amplitude. Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Part B The period. Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Part C 3.00 Nm x(t) = (2.0 cm)cos(10t − /4) t 2.00 cm 0.628 s Typesetting math: 100% The spring constant. Express your answer to three significant figures and include the appropriate units. ANSWER: Part D The phase constant. Express your answer to three significant figures and include the appropriate units. ANSWER: Incorrect; Try Again Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Part G Typesetting math: 100% This question will be shown after you complete previous question(s). Part H This question will be shown after you complete previous question(s). Part I This question will be shown after you complete previous question(s). Enhanced EOC: Problem 14.17 A spring with spring constant 16 hangs from the ceiling. A ball is attached to the spring and allowed to come to rest. It is then pulled down 4.0 and released. The ball makes 35 oscillations in 18 seconds. You may want to review ( pages 389 – 391) . For help with math skills, you may want to review: Differentiation of Trigonometric Functions Part A What is its the mass of the ball? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the period of oscillation? What is the angular frequency of the oscillations? How is the angular frequency related to the mass and spring constant? What is the mass? N/m cm s Typesetting math: 100% ANSWER: Correct Part B What is its maximum speed? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the amplitude of the oscillations? How is the maximum speed related to the amplitude of the oscillations and the angular frequency? ANSWER: Correct Changing the Period of a Pendulum A simple pendulum consisting of a bob of mass attached to a string of length swings with a period . Part A If the bob’s mass is doubled, approximately what will the pendulum’s new period be? Hint 1. Period of a simple pendulum The period of a simple pendulum of length is given by m = 110 g vmax = 49 cms m L T Typesetting math: 10T0% L , where is the acceleration due to gravity. ANSWER: Correct Part B If the pendulum is brought on the moon where the gravitational acceleration is about , approximately what will its period now be? Hint 1. How to approach the problem Recall the formula of the period of a simple pendulum. Since the gravitational acceleration appears in the denominator, the period must increase when the gravitational acceleration decreases. ANSWER: T = 2 Lg −−  g T/2 T &2T 2T g/6 T/6 T/&6 &6T 6T Typesetting math: 100% Correct Part C If the pendulum is taken into the orbiting space station what will happen to the bob? Hint 1. How to approach the problem Recall that the oscillations of a simple pendulum occur when a pendulum bob is raised above its equilibrium position and let go, causing the pendulum bob to fall. The gravitational force acts to bring the bob back to its equilibrium position. In the space station, the earth’s gravity acts on both the station and everything inside it, giving them the same acceleration. These objects are said to be in free fall. ANSWER: Correct In the space station, where all objects undergo the same acceleration due to the earth’s gravity, the tension in the string is zero and the bob does not fall relative to the point to which the string is attached. Problem 14.20 A 175 ball is tied to a string. It is pulled to an angle of 8.0 and released to swing as a pendulum. A student with a stopwatch finds that 15 oscillations take 13 . Part A How long is the string? Express your answer to two significant figures and include the appropriate units. It will continue to oscillate in a vertical plane with the same period. It will no longer oscillate because there is no gravity in space. It will no longer oscillate because both the pendulum and the point to which it is attached are in free fall. It will oscillate much faster with a period that approaches zero. g ( s Typesetting math: 100% ANSWER: Correct Problem 14.22 Part A What is the length of a pendulum whose period on the moon matches the period of a 2.1- -long pendulum on the earth? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 14.42 An ultrasonic transducer, of the type used in medical ultrasound imaging, is a very thin disk ( = 0.17 ) driven back and forth in SHM at by an electromagnetic coil. Part A The maximum restoring force that can be applied to the disk without breaking it is 4.4×104 . What is the maximum oscillation amplitude that won’t rupture the disk? Express your answer to two significant figures and include the appropriate units. ANSWER: L = 19 cm m lmoon = 0.35 m m g 1.0 MHz N amax = 6.6 μm Typesetting math: 100% Correct Part B What is the disk’s maximum speed at this amplitude? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 81.4%. You received 117.25 out of a possible total of 144 points. vmax = 41 ms

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In case the body have to stay in lower temperature for extended time period (more than 1 hour), how does the body regulate its response?

In case the body have to stay in lower temperature for extended time period (more than 1 hour), how does the body regulate its response?

Arterioles transporting blood to external capillaries beneath the surface of … Read More...
Chapter 04 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Activity: Investigating Survivorship Curves Click here to complete this activity. Then answer the questions. Part A Which of these species typically has a mortality rate that remains fairly constant over an individual’s life span? ANSWER: Correct The mortality rate of robins remains relatively constant throughout their life span. Part B Oyster populations are primarily, if not exclusively, composed of _____. ANSWER: Correct Young oysters have a very high mortality rate; older oysters have a much lower mortality rate. Thus, most oyster populations consist primarily of older individuals. Part C Which of these organisms has a survivorship curve similar to that of oysters? ANSWER: grasses oysters elephants robins humans juveniles adults prereproductive oysters larval and juvenile oysters larvae Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 13 5/21/2014 7:59 PM Correct Grasses, like oysters, have a relatively high mortality rate early in their life span, after which the mortality rate decreases. Part D Which of these organisms has a survivorship curve similar to that of humans? ANSWER: Correct The mortality rate of elephants, like that of humans, remains relatively low for much of their life span and then dramatically increases for older individuals. BioFlix Quiz: Population Ecology Watch the animation at left before answering the questions below. cats robins elephants grasses humans cats oysters grasses robins elephants Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 13 5/21/2014 7:59 PM Part A An ideal habitat with unlimited resources is associated with Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Populations grow exponentially with unlimited resources. Part B The maximum population a habitat can support is its Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Part C Logistic growth involves Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Both exponential growth and logistic growth. Population crashes. Exponential growth. Logistic growth. Neither exponential growth nor logistic growth. Logistic growth. Death rate. Birth rate. Carrying capacity. Exponential growth. A population crash. Population growth continuing forever. Population growth reaching carrying capacity and then speeding up. Population size decreasing to zero. Population growth slowing down as the population approaches carrying capacity. Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 13 5/21/2014 7:59 PM Correct Part D In exponential growth Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Part E Which of the following would NOT cause population size to decrease? Hint 1. Review the animation. ANSWER: Correct An increased birth rate would cause population size to increase. BioFlix Activity: Photosynthesis — Inputs and Outputs Can you fill in the photosynthesis equation? To review photosynthesis, watch this BioFlix animation: Photosynthesis. Part A – Photosynthesis equation Drag the labels onto the equation to identify the inputs and outputs of photosynthesis. ANSWER: Population size grows more and more slowly as the population gets bigger. Population size grows faster and faster as the population gets bigger. Population size stays constant. Population growth slows as the population gets close to its carrying capacity. None of these are correct. Increased death rate A exponentially growing population outgrowing its food supply and crashing Poor weather, resulting in less food being available Increase in the number of predators Increased birth rate Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 13 5/21/2014 7:59 PM BioFlix Activity: Cellular Respiration and Photosynthesis — Energy Flow Can you identify how energy flows through an ecosystem? To review energy flow in cellular respiration and photosynthesis, watch these BioFlix animations: Cellular Respiration and Photosynthesis. Part A – Energy flow through an ecosystem Drag the labels onto the diagram to identify how energy flows through an ecosystem. ANSWER: BioFlix Activity: Cellular Respiration and Photosynthesis — Chemical Cycling Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 13 5/21/2014 7:59 PM Can you identify how chemicals cycle in an ecosystem? To review the chemical inputs and outputs of cellular respiration and photosynthesis, watch these BioFlix animations: Cellular Respiration and Photosynthesis. Part A – Chemical cycling in an ecosystem Drag the labels onto the diagram to identify how chemicals cycle in an ecosystem. ANSWER: BioFlix Activity: Cellular Respiration — Inputs and Outputs Can you fill in the cellular respiration equation? To review cellular respiration, watch this BioFlix animation: Cellular Respiration. Part A – Cellular respiration equation Drag the labels onto the equation to identify the inputs and outputs of cellular respiration. ANSWER: Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 13 5/21/2014 7:59 PM BioFlix Activity: Population Ecology — Types of Population Growth Can you identify the different ways in which populations grow? To review types of population growth, watch this BioFlix animation: Population Ecology. Part A – Types of population growth Drag the correct label under each graph to identify the type of population growth shown. ANSWER: Concept Review: Calculating Doubling Time Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 13 5/21/2014 7:59 PM Can you calculate doubling times and growth rates for exponentially growing populations? Remember that the doubling time (in years) for an exponentially growing population is estimated by dividing 70 by the growth rate of the population (as a percentage): Doubling time (in years) = 70 / annual growth rate (%) Part A Drag the values on the left to the appropriate blanks on the right to complete the sentences. Not all values will be used. ANSWER: Concept Review: Calculating Population Growth Rates Populations grow larger from births and immigration and grow smaller from deaths and emigration. The growth rate for a population is determined by adding the birth rate and the immigration rate, and then subtracting the death rate and the emigration rate (all rates expressed as the number per 1,000 individuals per year): (birth rate + immigration rate) (death rate + emigration rate) = growth rate Positive population growth rates lead to population increases, and negative population growth rates lead to population declines. Part A Suppose you are studying a population with the following characteristics: Birth rate = 14 per 1,000/year Death rate = 6 per 1,000/year Immigration rate = 5 per 1,000/year Emigration rate = 1 per 1,000/year What is the growth rate for this population? ANSWER: Part B Suppose you are studying a population with the following characteristics: 4 per 1,000/year 12 per 1,000/year 14 per 1,000/year 26 per 1,000/year Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 13 5/21/2014 7:59 PM Birth rate = 11 per 1,000/year Death rate = 10 per 1,000/year Immigration rate = 4 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? ANSWER: Part C Suppose you are studying a population with the following characteristics: Birth rate = 10 per 1,000/year Death rate = 12 per 1,000/year Immigration rate = 2 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? ANSWER: Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Concept Review: Levels of Ecological Organization Can you identify the example that corresponds to each level of ecological organization? Part A Drag the labels to the appropriate targets in the table. ANSWER: 0 per 1,000/year 2 per 1,000/year 14 per 1,000/year 28 per 1,000/year 3 per 1,000/year 1 per 1,000/year 17 per 1,000/year 27 per 1,000/year Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 9 of 13 5/21/2014 7:59 PM BioFlix Activity: Mechanisms of Evolution — Natural Selection: Pesticides Can you identify the process by which natural selection acts on an insect population exposed to pesticides? To review the process of natural selection, watch this BioFlix animation: Mechanisms of Evolution: Natural Selection. Part A – Natural selection: Pesticides Drag the labels onto the flowchart to place them in the correct sequence. ANSWER: Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 10 of 13 5/21/2014 7:59 PM ABC News Video: Protecting the Galapagos Islands Watch the ABC News video (2:07 minutes). Then answer the questions below. Part A Where are the Galapagos Islands located? ANSWER: Part B Which of the following sets of animals are likely to be found on the Galapagos Islands? ANSWER: near the tip of South Africa northeast of Australia along the Great Barrier Reef 600 miles west of Ecuador, near the equator in the Mediterranean Sea, as part of the Greek Islands frogs, lungfish, mountain goats tortoises, finches, blue-footed boobies ostriches, cougars, porcupines beaver, snakes, armadillos Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 11 of 13 5/21/2014 7:59 PM Part C Which species is threatening the natural wildlife on the Galapagos Islands? ANSWER: Part D The Galapagos Islands were the first place on Earth to _____. ANSWER: Part E Tourism on the Galapagos Islands is being restricted by requiring tourists to _____. ANSWER: Current Events: A Surplus Washington Could Do Without: A Capital Park’s Rapacious Deer (New York Times, 2/28/2012) Read this New York Times article and then answer the questions. A Surplus Washington Could Do Without: A Capital Park’s Rapacious Deer (2/28/2012) Registration with The New York Times provides instant access to breaking news on NYTimes.com. To register, go to http://www.nytimes.com/register. Visit http://www.nytimes.com/content/help/rights/terms/terms-of-service.html to review the current NYT Terms of Service. Part A Which of the following is true? ANSWER: Part B What predator currently feeds on deer in Rock Creek Park? humans zebra mussels Asian carp mountain lions suffer the complete extinction of all native species be declared off-limits to all humans be declared a world heritage site be invaded by human-introduced species visit each island in groups of only ten individuals at a time view the islands only from the water be escorted by trained guides at all times stay at least 100 feet away from all animals on the islands Deer have always been a problem in Rock Creek Park. Deer are not a problem in Rock Creek Park. Deer are not native to Rock Creek Park, and have been a problem since they were introduced in 1952. Deer were once absent from Rock Creek Park, and have only become a problem in the last 20 years. Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 12 of 13 5/21/2014 7:59 PM ANSWER: Part C Why isn’t the deer population controlled by hunting in Rock Creek Park? ANSWER: Part D It is hoped that the deer herd can be reduced by how much? ANSWER: Part E Which of the following is true? ANSWER: Part F Because the park is changing in response to the increasing deer population, this is an example of ______________. ANSWER: Score Summary: Your score on this assignment is 21.2%. You received 9.1 out of a possible total of 43 points. There are no predators of deer in Rock Creek Park. mountain lion coyote wolf Hunting has been attempted in the park, but the trees are too thick. Hunting is prohibited in the park. There is no public interest in hunting in the park. Deer are a protected species. one-quarter one-half three-quarters the entire herd Animals cannot be killed on federally managed public lands. Only Congress can decide to have animals killed on federally managed public lands. The federal agency in charge of management of the land in question decides if animals should be killed. Only the National Park Service can decide to have animals killed on federally managed public lands. succession artificial selection recession progression Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 13 of 13 5/21/2014 7:59 PM

Chapter 04 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Activity: Investigating Survivorship Curves Click here to complete this activity. Then answer the questions. Part A Which of these species typically has a mortality rate that remains fairly constant over an individual’s life span? ANSWER: Correct The mortality rate of robins remains relatively constant throughout their life span. Part B Oyster populations are primarily, if not exclusively, composed of _____. ANSWER: Correct Young oysters have a very high mortality rate; older oysters have a much lower mortality rate. Thus, most oyster populations consist primarily of older individuals. Part C Which of these organisms has a survivorship curve similar to that of oysters? ANSWER: grasses oysters elephants robins humans juveniles adults prereproductive oysters larval and juvenile oysters larvae Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 13 5/21/2014 7:59 PM Correct Grasses, like oysters, have a relatively high mortality rate early in their life span, after which the mortality rate decreases. Part D Which of these organisms has a survivorship curve similar to that of humans? ANSWER: Correct The mortality rate of elephants, like that of humans, remains relatively low for much of their life span and then dramatically increases for older individuals. BioFlix Quiz: Population Ecology Watch the animation at left before answering the questions below. cats robins elephants grasses humans cats oysters grasses robins elephants Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 13 5/21/2014 7:59 PM Part A An ideal habitat with unlimited resources is associated with Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Populations grow exponentially with unlimited resources. Part B The maximum population a habitat can support is its Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Part C Logistic growth involves Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Both exponential growth and logistic growth. Population crashes. Exponential growth. Logistic growth. Neither exponential growth nor logistic growth. Logistic growth. Death rate. Birth rate. Carrying capacity. Exponential growth. A population crash. Population growth continuing forever. Population growth reaching carrying capacity and then speeding up. Population size decreasing to zero. Population growth slowing down as the population approaches carrying capacity. Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 13 5/21/2014 7:59 PM Correct Part D In exponential growth Hint 1. Review the animation or your Study Sheet for Population Ecology ANSWER: Correct Part E Which of the following would NOT cause population size to decrease? Hint 1. Review the animation. ANSWER: Correct An increased birth rate would cause population size to increase. BioFlix Activity: Photosynthesis — Inputs and Outputs Can you fill in the photosynthesis equation? To review photosynthesis, watch this BioFlix animation: Photosynthesis. Part A – Photosynthesis equation Drag the labels onto the equation to identify the inputs and outputs of photosynthesis. ANSWER: Population size grows more and more slowly as the population gets bigger. Population size grows faster and faster as the population gets bigger. Population size stays constant. Population growth slows as the population gets close to its carrying capacity. None of these are correct. Increased death rate A exponentially growing population outgrowing its food supply and crashing Poor weather, resulting in less food being available Increase in the number of predators Increased birth rate Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 13 5/21/2014 7:59 PM BioFlix Activity: Cellular Respiration and Photosynthesis — Energy Flow Can you identify how energy flows through an ecosystem? To review energy flow in cellular respiration and photosynthesis, watch these BioFlix animations: Cellular Respiration and Photosynthesis. Part A – Energy flow through an ecosystem Drag the labels onto the diagram to identify how energy flows through an ecosystem. ANSWER: BioFlix Activity: Cellular Respiration and Photosynthesis — Chemical Cycling Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 13 5/21/2014 7:59 PM Can you identify how chemicals cycle in an ecosystem? To review the chemical inputs and outputs of cellular respiration and photosynthesis, watch these BioFlix animations: Cellular Respiration and Photosynthesis. Part A – Chemical cycling in an ecosystem Drag the labels onto the diagram to identify how chemicals cycle in an ecosystem. ANSWER: BioFlix Activity: Cellular Respiration — Inputs and Outputs Can you fill in the cellular respiration equation? To review cellular respiration, watch this BioFlix animation: Cellular Respiration. Part A – Cellular respiration equation Drag the labels onto the equation to identify the inputs and outputs of cellular respiration. ANSWER: Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 13 5/21/2014 7:59 PM BioFlix Activity: Population Ecology — Types of Population Growth Can you identify the different ways in which populations grow? To review types of population growth, watch this BioFlix animation: Population Ecology. Part A – Types of population growth Drag the correct label under each graph to identify the type of population growth shown. ANSWER: Concept Review: Calculating Doubling Time Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 13 5/21/2014 7:59 PM Can you calculate doubling times and growth rates for exponentially growing populations? Remember that the doubling time (in years) for an exponentially growing population is estimated by dividing 70 by the growth rate of the population (as a percentage): Doubling time (in years) = 70 / annual growth rate (%) Part A Drag the values on the left to the appropriate blanks on the right to complete the sentences. Not all values will be used. ANSWER: Concept Review: Calculating Population Growth Rates Populations grow larger from births and immigration and grow smaller from deaths and emigration. The growth rate for a population is determined by adding the birth rate and the immigration rate, and then subtracting the death rate and the emigration rate (all rates expressed as the number per 1,000 individuals per year): (birth rate + immigration rate) (death rate + emigration rate) = growth rate Positive population growth rates lead to population increases, and negative population growth rates lead to population declines. Part A Suppose you are studying a population with the following characteristics: Birth rate = 14 per 1,000/year Death rate = 6 per 1,000/year Immigration rate = 5 per 1,000/year Emigration rate = 1 per 1,000/year What is the growth rate for this population? ANSWER: Part B Suppose you are studying a population with the following characteristics: 4 per 1,000/year 12 per 1,000/year 14 per 1,000/year 26 per 1,000/year Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 13 5/21/2014 7:59 PM Birth rate = 11 per 1,000/year Death rate = 10 per 1,000/year Immigration rate = 4 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? ANSWER: Part C Suppose you are studying a population with the following characteristics: Birth rate = 10 per 1,000/year Death rate = 12 per 1,000/year Immigration rate = 2 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? ANSWER: Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). Concept Review: Levels of Ecological Organization Can you identify the example that corresponds to each level of ecological organization? Part A Drag the labels to the appropriate targets in the table. ANSWER: 0 per 1,000/year 2 per 1,000/year 14 per 1,000/year 28 per 1,000/year 3 per 1,000/year 1 per 1,000/year 17 per 1,000/year 27 per 1,000/year Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 9 of 13 5/21/2014 7:59 PM BioFlix Activity: Mechanisms of Evolution — Natural Selection: Pesticides Can you identify the process by which natural selection acts on an insect population exposed to pesticides? To review the process of natural selection, watch this BioFlix animation: Mechanisms of Evolution: Natural Selection. Part A – Natural selection: Pesticides Drag the labels onto the flowchart to place them in the correct sequence. ANSWER: Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 10 of 13 5/21/2014 7:59 PM ABC News Video: Protecting the Galapagos Islands Watch the ABC News video (2:07 minutes). Then answer the questions below. Part A Where are the Galapagos Islands located? ANSWER: Part B Which of the following sets of animals are likely to be found on the Galapagos Islands? ANSWER: near the tip of South Africa northeast of Australia along the Great Barrier Reef 600 miles west of Ecuador, near the equator in the Mediterranean Sea, as part of the Greek Islands frogs, lungfish, mountain goats tortoises, finches, blue-footed boobies ostriches, cougars, porcupines beaver, snakes, armadillos Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 11 of 13 5/21/2014 7:59 PM Part C Which species is threatening the natural wildlife on the Galapagos Islands? ANSWER: Part D The Galapagos Islands were the first place on Earth to _____. ANSWER: Part E Tourism on the Galapagos Islands is being restricted by requiring tourists to _____. ANSWER: Current Events: A Surplus Washington Could Do Without: A Capital Park’s Rapacious Deer (New York Times, 2/28/2012) Read this New York Times article and then answer the questions. A Surplus Washington Could Do Without: A Capital Park’s Rapacious Deer (2/28/2012) Registration with The New York Times provides instant access to breaking news on NYTimes.com. To register, go to http://www.nytimes.com/register. Visit http://www.nytimes.com/content/help/rights/terms/terms-of-service.html to review the current NYT Terms of Service. Part A Which of the following is true? ANSWER: Part B What predator currently feeds on deer in Rock Creek Park? humans zebra mussels Asian carp mountain lions suffer the complete extinction of all native species be declared off-limits to all humans be declared a world heritage site be invaded by human-introduced species visit each island in groups of only ten individuals at a time view the islands only from the water be escorted by trained guides at all times stay at least 100 feet away from all animals on the islands Deer have always been a problem in Rock Creek Park. Deer are not a problem in Rock Creek Park. Deer are not native to Rock Creek Park, and have been a problem since they were introduced in 1952. Deer were once absent from Rock Creek Park, and have only become a problem in the last 20 years. Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 12 of 13 5/21/2014 7:59 PM ANSWER: Part C Why isn’t the deer population controlled by hunting in Rock Creek Park? ANSWER: Part D It is hoped that the deer herd can be reduced by how much? ANSWER: Part E Which of the following is true? ANSWER: Part F Because the park is changing in response to the increasing deer population, this is an example of ______________. ANSWER: Score Summary: Your score on this assignment is 21.2%. You received 9.1 out of a possible total of 43 points. There are no predators of deer in Rock Creek Park. mountain lion coyote wolf Hunting has been attempted in the park, but the trees are too thick. Hunting is prohibited in the park. There is no public interest in hunting in the park. Deer are a protected species. one-quarter one-half three-quarters the entire herd Animals cannot be killed on federally managed public lands. Only Congress can decide to have animals killed on federally managed public lands. The federal agency in charge of management of the land in question decides if animals should be killed. Only the National Park Service can decide to have animals killed on federally managed public lands. succession artificial selection recession progression Chapter 04 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 13 of 13 5/21/2014 7:59 PM

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In your opinion, will BitCoins stick around? Why or Why Not?

In your opinion, will BitCoins stick around? Why or Why Not?

In your opinion, will BitCoins stick around? Why or Why … Read More...
Chapter 05 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Activity: Human Population Growth Click here to complete this activity. Then answer the questions. Part A Which of these was the first of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The advent of agriculture is the first of the events listed here that stimulated an increase in the size of the human population. Part B Which of these was the second of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The Industrial Revolution was the second of the major events that stimulated an increase in the size of the human population. Part C Which of these was the third of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The advent of modern medicine is the third and most recent of the events listed here that have stimulated an increase in the population size of humans. the Industrial Revolution the advent of agriculture the discovery of antibiotics the bubonic plague the discovery of vaccines the discovery of vaccines the discovery of antibiotics the advent of agriculture the Industrial Revolution the bubonic plague the discovery of vaccines the advent of agriculture the discovery of antibiotics the discovery of vaccines and the discovery of antibiotics the Industrial Revolution Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 8 5/21/2014 8:00 PM Part D Currently, how large is the worldwide population of humans relative to Earth’s carrying capacity for humans? ANSWER: Correct Not knowing how technological innovations will affect the human population means there is insufficient information to answer this question. Activity: Analyzing Age-Structure Pyramids Click here to complete this activity. Then answer the questions. Part A Ignoring migration, the age structure of a human population likely to increase in size will have what shape? ANSWER: Correct This would mean that most individuals are in the prereproductive years. Such a population is expected to increase. Part B Ignoring migration, the age structure of a human population likely to decrease in size will have what shape? ANSWER: Correct In such a population the majority of individuals are in their postreproductive years. Such a population is expected to decrease. Part C Ignoring migration, the age structure diagram of a human population likely to maintain a relatively stable size will have what shape? There is insufficient information to answer this question. either at or above the carrying capacity below the carrying capacity above the carrying capacity at the carrying capacity Both an inverted pyramid and a rectangle tapering toward the top result in a population that increases in size. pyramid Both a pyramid and a rectangle tapering toward the top result in a population that increases in size. a rectangle tapering toward the top inverted pyramid pyramid Both an inverted pyramid and a rectangle tapering toward the top result in a population that decreases in size. Both a pyramid and a rectangle tapering toward the top result in a population that decreases in size. a rectangle tapering toward the top inverted pyramid Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 8 5/21/2014 8:00 PM ANSWER: Correct Such a population is expected to have a relatively stable size. GraphIt!: Age Pyramids and Population Growth Click here to complete the graphing activity. Then answer the questions. Part A – Question 1 The population of Greece is expected to _______. Hint 1. Review Step 2 of this activity. What shape does this population have? ANSWER: Correct Part B – Question 2 Assuming the current trend continues, in 30 years Greece will have more children than reproductive-age individuals. Hint 1. What age group will today’s newborns occupy in 2030? ANSWER: Correct Part C – Question 3 Assuming the current trend continues, in 30 years Greece will have more children than elderly members of the population. Hint 1. Both an inverted pyramid and a rectangle tapering toward the top result in a population that remains stable in size. pyramid Both a pyramid and a rectangle tapering toward the top result in a population that remains stable in size. inverted pyramid a rectangle tapering toward the top expand remain stable decline True False Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 8 5/21/2014 8:00 PM What age groups will today’s reproductive-age individuals occupy in 2030? ANSWER: Correct Part D – Question 4 Assuming the current trend continues, in 30 years Greece will have more reproductive-age individuals than children. ANSWER: Correct Part E – Question 5 Assuming the current trend continues, in 30 years Greece will have more elderly than reproductive-age individuals. ANSWER: Correct Part F – Question 6 Greece had more females than males in 2000. Which of the following is the most likely explanation for this? Hint 1. Which sex tends to live longer in the United States, males or females? ANSWER: Correct Part G – Question 7 The population of Colombia is currently _______. Hint 1. Review Step 2 of this activity. What shape does this population have? ANSWER: True False True False True False Females generally have a shorter life span than males. More females are born than males, and this difference remains throughout all age groups. There should be an equal number of males and females in every age group, so this is likely an error in the 2000 census for Greece. Males generally have a shorter life span than females. expanding stable declining Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 8 5/21/2014 8:00 PM Correct Part H – Question 8 Assuming the current trend continues, in 30 years Colombia will have more children than reproductive-age individuals. Hint 1. What age group will today’s newborns occupy in 2030? ANSWER: Correct Part I – Question 9 Assuming the current trend continues, in 30 years Colombia will have more children than elderly members of the population. Hint 1. What age groups will today’s reproductive-age individuals occupy in 2030? ANSWER: Correct Part J – Question 10 Assuming the current trend continues, in 30 years Colombia will have more reproductive-age individuals than children. ANSWER: Correct Part K – Question 11 Assuming the current trend continues, in 30 years Colombia will have more elderly than reproductive-age individuals. ANSWER: Correct Concept Review: Demographic Transition Model Can you identify what happens in each stage of the demographic transition model? Part A Drag the labels to the appropriate targets. ANSWER: True False True False True False True False Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 8 5/21/2014 8:00 PM Answer Requested Concept Review: Demographic Characteristics of Developed and Developing Nations For each demographic characteristic described in the table below, decide whether it applies to developed nations, developing nations, or neither group. Part A Drag the correct labels onto the table. Labels may be used once, more than once, or not at all. ANSWER: Concept Review: Age Structure Diagrams Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 8 5/21/2014 8:00 PM Can you label age structure diagrams? Part A Drag the labels to the appropriate targets. Pink labels indicate what each age class represents. Blue labels indicate how the population is expected to change over time. ANSWER: Correct Current Events: Nigeria Tested by Rapid Rise in Population (New York Times, 4/14/2012) Read this New York Times article and then answer the questions. Nigeria Tested by Rapid Rise in Population (4/14/2012) Registration with The New York Times provides instant access to breaking news on NYTimes.com. To register, go to http://www.nytimes.com/register. Visit http://www.nytimes.com /content/help/rights/terms/terms-of-service.html to review the current NYT Terms of Service. Part A The current human population is just over _______ billion people. ANSWER: Correct Part B How are the governments of sub-Saharan Africa reacting to a rapidly increasing population? ANSWER: Part C Which of the following tends to be true? ANSWER: 6 7 8 9 They are beginning to encourage people to have fewer children. They are doing nothing. They are waiting to hear the recommendations from the United Nations. They are still encouraging people to have many children. Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 8 5/21/2014 8:00 PM Part D You are in the Nigerian government and are working on trying to solve the problem of a rapidly increasing population. You decide to incorporate the Latin American model as part of your plan. Which of the following do you recommend? ANSWER: Part E If nearly every adult in a society is married and polygamy is common, which of the following is true? ANSWER: Part F Even if global total fertility rate drops to 2.1, estimates indicate that the human population will reach ________ by 2100. ANSWER: Score Summary: Your score on this assignment is 57.9%. You received 15.06 out of a possible total of 26 points. The relationship between changing population and unemployment rates is too variable to quantify. An increase in population leads to an increase in unemployment. Population growth and unemployment are not correlated. An increase in population leads to a decrease in unemployment. There will be tax breaks for families with fewer children. Girls will be required to finish high school. The government will impose a limit of only one child. The government will provide free family planning. There are more adult women than adult men. There are equal numbers of adult men and adult women. There are more adult men than adult women. The ratio of adult men to adult women would depend on the total fertility rate. 10 billion 12 billion 14 billion 16 billion Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 8 5/21/2014 8:00 PM

Chapter 05 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Activity: Human Population Growth Click here to complete this activity. Then answer the questions. Part A Which of these was the first of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The advent of agriculture is the first of the events listed here that stimulated an increase in the size of the human population. Part B Which of these was the second of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The Industrial Revolution was the second of the major events that stimulated an increase in the size of the human population. Part C Which of these was the third of the major events that stimulated an increase in the size of the human population? ANSWER: Correct The advent of modern medicine is the third and most recent of the events listed here that have stimulated an increase in the population size of humans. the Industrial Revolution the advent of agriculture the discovery of antibiotics the bubonic plague the discovery of vaccines the discovery of vaccines the discovery of antibiotics the advent of agriculture the Industrial Revolution the bubonic plague the discovery of vaccines the advent of agriculture the discovery of antibiotics the discovery of vaccines and the discovery of antibiotics the Industrial Revolution Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 8 5/21/2014 8:00 PM Part D Currently, how large is the worldwide population of humans relative to Earth’s carrying capacity for humans? ANSWER: Correct Not knowing how technological innovations will affect the human population means there is insufficient information to answer this question. Activity: Analyzing Age-Structure Pyramids Click here to complete this activity. Then answer the questions. Part A Ignoring migration, the age structure of a human population likely to increase in size will have what shape? ANSWER: Correct This would mean that most individuals are in the prereproductive years. Such a population is expected to increase. Part B Ignoring migration, the age structure of a human population likely to decrease in size will have what shape? ANSWER: Correct In such a population the majority of individuals are in their postreproductive years. Such a population is expected to decrease. Part C Ignoring migration, the age structure diagram of a human population likely to maintain a relatively stable size will have what shape? There is insufficient information to answer this question. either at or above the carrying capacity below the carrying capacity above the carrying capacity at the carrying capacity Both an inverted pyramid and a rectangle tapering toward the top result in a population that increases in size. pyramid Both a pyramid and a rectangle tapering toward the top result in a population that increases in size. a rectangle tapering toward the top inverted pyramid pyramid Both an inverted pyramid and a rectangle tapering toward the top result in a population that decreases in size. Both a pyramid and a rectangle tapering toward the top result in a population that decreases in size. a rectangle tapering toward the top inverted pyramid Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 8 5/21/2014 8:00 PM ANSWER: Correct Such a population is expected to have a relatively stable size. GraphIt!: Age Pyramids and Population Growth Click here to complete the graphing activity. Then answer the questions. Part A – Question 1 The population of Greece is expected to _______. Hint 1. Review Step 2 of this activity. What shape does this population have? ANSWER: Correct Part B – Question 2 Assuming the current trend continues, in 30 years Greece will have more children than reproductive-age individuals. Hint 1. What age group will today’s newborns occupy in 2030? ANSWER: Correct Part C – Question 3 Assuming the current trend continues, in 30 years Greece will have more children than elderly members of the population. Hint 1. Both an inverted pyramid and a rectangle tapering toward the top result in a population that remains stable in size. pyramid Both a pyramid and a rectangle tapering toward the top result in a population that remains stable in size. inverted pyramid a rectangle tapering toward the top expand remain stable decline True False Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 8 5/21/2014 8:00 PM What age groups will today’s reproductive-age individuals occupy in 2030? ANSWER: Correct Part D – Question 4 Assuming the current trend continues, in 30 years Greece will have more reproductive-age individuals than children. ANSWER: Correct Part E – Question 5 Assuming the current trend continues, in 30 years Greece will have more elderly than reproductive-age individuals. ANSWER: Correct Part F – Question 6 Greece had more females than males in 2000. Which of the following is the most likely explanation for this? Hint 1. Which sex tends to live longer in the United States, males or females? ANSWER: Correct Part G – Question 7 The population of Colombia is currently _______. Hint 1. Review Step 2 of this activity. What shape does this population have? ANSWER: True False True False True False Females generally have a shorter life span than males. More females are born than males, and this difference remains throughout all age groups. There should be an equal number of males and females in every age group, so this is likely an error in the 2000 census for Greece. Males generally have a shorter life span than females. expanding stable declining Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 8 5/21/2014 8:00 PM Correct Part H – Question 8 Assuming the current trend continues, in 30 years Colombia will have more children than reproductive-age individuals. Hint 1. What age group will today’s newborns occupy in 2030? ANSWER: Correct Part I – Question 9 Assuming the current trend continues, in 30 years Colombia will have more children than elderly members of the population. Hint 1. What age groups will today’s reproductive-age individuals occupy in 2030? ANSWER: Correct Part J – Question 10 Assuming the current trend continues, in 30 years Colombia will have more reproductive-age individuals than children. ANSWER: Correct Part K – Question 11 Assuming the current trend continues, in 30 years Colombia will have more elderly than reproductive-age individuals. ANSWER: Correct Concept Review: Demographic Transition Model Can you identify what happens in each stage of the demographic transition model? Part A Drag the labels to the appropriate targets. ANSWER: True False True False True False True False Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 8 5/21/2014 8:00 PM Answer Requested Concept Review: Demographic Characteristics of Developed and Developing Nations For each demographic characteristic described in the table below, decide whether it applies to developed nations, developing nations, or neither group. Part A Drag the correct labels onto the table. Labels may be used once, more than once, or not at all. ANSWER: Concept Review: Age Structure Diagrams Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 8 5/21/2014 8:00 PM Can you label age structure diagrams? Part A Drag the labels to the appropriate targets. Pink labels indicate what each age class represents. Blue labels indicate how the population is expected to change over time. ANSWER: Correct Current Events: Nigeria Tested by Rapid Rise in Population (New York Times, 4/14/2012) Read this New York Times article and then answer the questions. Nigeria Tested by Rapid Rise in Population (4/14/2012) Registration with The New York Times provides instant access to breaking news on NYTimes.com. To register, go to http://www.nytimes.com/register. Visit http://www.nytimes.com /content/help/rights/terms/terms-of-service.html to review the current NYT Terms of Service. Part A The current human population is just over _______ billion people. ANSWER: Correct Part B How are the governments of sub-Saharan Africa reacting to a rapidly increasing population? ANSWER: Part C Which of the following tends to be true? ANSWER: 6 7 8 9 They are beginning to encourage people to have fewer children. They are doing nothing. They are waiting to hear the recommendations from the United Nations. They are still encouraging people to have many children. Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 8 5/21/2014 8:00 PM Part D You are in the Nigerian government and are working on trying to solve the problem of a rapidly increasing population. You decide to incorporate the Latin American model as part of your plan. Which of the following do you recommend? ANSWER: Part E If nearly every adult in a society is married and polygamy is common, which of the following is true? ANSWER: Part F Even if global total fertility rate drops to 2.1, estimates indicate that the human population will reach ________ by 2100. ANSWER: Score Summary: Your score on this assignment is 57.9%. You received 15.06 out of a possible total of 26 points. The relationship between changing population and unemployment rates is too variable to quantify. An increase in population leads to an increase in unemployment. Population growth and unemployment are not correlated. An increase in population leads to a decrease in unemployment. There will be tax breaks for families with fewer children. Girls will be required to finish high school. The government will impose a limit of only one child. The government will provide free family planning. There are more adult women than adult men. There are equal numbers of adult men and adult women. There are more adult men than adult women. The ratio of adult men to adult women would depend on the total fertility rate. 10 billion 12 billion 14 billion 16 billion Chapter 05 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 8 5/21/2014 8:00 PM

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Critical Thinking: How much stress is too much? The level of stress a person can experience before it does harm to the human body remains an important question. In a study of medical students, many working between 70-80 hours per week, nearly half suffered from extremely high levels of stress. In general, the more hours worked, the greater the level of stress experienced by the student. Higher levels of stress often corresponded with unhealthy coping strategies, including drug and alcohol abuse (Kasi et al., 2007) In addition, the study found that the students’ stress level also put their patients at risk. Stressed residents were more likely to make errors and to compromise patient care (Pitt et al., 2004).

Critical Thinking: How much stress is too much? The level of stress a person can experience before it does harm to the human body remains an important question. In a study of medical students, many working between 70-80 hours per week, nearly half suffered from extremely high levels of stress. In general, the more hours worked, the greater the level of stress experienced by the student. Higher levels of stress often corresponded with unhealthy coping strategies, including drug and alcohol abuse (Kasi et al., 2007) In addition, the study found that the students’ stress level also put their patients at risk. Stressed residents were more likely to make errors and to compromise patient care (Pitt et al., 2004).

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Chapter 05 Reading Questions Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Chapter 5 Reading Quiz Question 1 Part A In the second stage of the demographic transition, called the mortality transition, the death rate _____ while the birth rate _____. ANSWER: Chapter 5 Reading Quiz Question 2 Part A About a century ago, the population in Latin America moved from an agricultural to an urban-industrial base. During this period birth rates _____, death rates _____, and the overall population _____. ANSWER: Chapter 5 Reading Quiz Question 16 Part A Over the course of human history, the greatest increases in human populations have been due to_____. ANSWER: increases, decreases decreases, decreases decreases, remains high or increases increases, remains high or increases stayed about the same, decreased, and the population grew even faster increased greatly, increased, declined decreased dramatically, decreased, declined stayed about the same, increased, increased Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 4 Part A Compared to women in the United States, women in poor countries such as Ethiopia typically have _____ children at _____ age. ANSWER: Chapter 5 Reading Quiz Question 18 Part A Women in two developed countries have similar total fertility rates of 3.5. However, women in country A typically have their children about 2 years earlier than women in country B. How will the populations of the two countries compare? ANSWER: Chapter 5 Reading Quiz Question 19 Part A Overall population growth rates are most likely to be highest when the median age of a population is _____ and a country is in stage _____ of the demographic transition. ANSWER: improved medicine improved water supplies discovery of new land increased food production fewer, an older more, a younger more, an older fewer, a younger The population of country B will increase faster than country A. The population of country A will increase but the population of country B will decline. The population of country A will increase faster than country B. The populations of both countries will be stable, with similar totals and little increase or decrease. Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 20 Part A An age-structure diagram of a poor country in stage 1 of the demographic transition will be closest to the shape of _____. ANSWER: Chapter 5 Reading Quiz Question 8 Part A Predictions about global growth rates have been difficult because of changes in human values and behavior largely based upon _____. ANSWER: Chapter 5 Reading Quiz Question 9 Part A Because human suffering _____ as the human population approaches its carrying capacity, sustainability of the global human population must be _____ the carrying capacity of the Earth. ANSWER: older, 1 younger, 4 older, 3 younger, 2 the letter O, widest in the middle a pyramid, with a broad base and narrow top the letter V, widest at the top column, with even width from top to bottom shifting weather patterns increasing abilities to travel between countries the spread of infectious disease economic development Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 10 Part A The IPAT formula is used to estimate the _____. ANSWER: Chapter 5 Reading Quiz Question 12 Part A If everyone in the world had the ecological footprint of people currently living in the United States and Canada, the world would _____. ANSWER: Chapter 5 Reading Quiz Question 22 Part A If the population of the United States continues to grow and consumption levels also increase, we expect that the _____. ANSWER: increases, below decreases, above increases, above decreases, below birth rate of a population shift from one stage to another in the demographic transition age structure of a population ecological footprint of a society have just enough biocapacity without any additional population growth exceed its biocapacity by 40% still have enough biocapacity for 20% more humans exceed its biocapacity by five times over Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 24 Part A Given the increasing global population and increased rates of consumption in developing countries, the most likely avenue to sustainability is _____. ANSWER: Chapter 5 Reading Quiz Question 13 Part A Which one of the following typically contributes to population growth? ANSWER: Chapter 5 Reading Quiz Question 14 Part A Members of the neo-Malthusian movement advocated for _____. ANSWER: ecological footprint will eventually exceed the biocapacity of the environment biocapacity will eventually exceed the ecological footprint of the environment United States will eventually become an ecological debtor ecological debt of the United States will continue to increase more efficient use of natural resources the discovery of ways to dramatically increase the global biocapacity to have developed countries use more natural resources from developing countries increase our reliance upon fossil fuels better education empowerment of women high infant mortality economic development Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 15 Part A China, Mexico, and India have all made progress in reducing the population growth rates in their countries by adopting policies that encourage _____. ANSWER: Chapter 5 Reading Quiz Question 7 Part A Malthus found that populations in the American colonies were increasing _____ than populations on the European continent due to _____. ANSWER: Score Summary: Your score on this assignment is 0.0%. You received 0 out of a possible total of 17 points. increasing population size to support greater economic development birth control to limit population growth greater use of natural resources to increase the biocapacity of Earth to support a growing human population greater conservation of natural resources to limit the environmental impact of a growing human population limits on family size women to work only inside of their homes women to start having children at a younger age couples to marry earlier faster, no political conflicts or wars faster, greater resources were available in the American colonies slower, fewer resources were available in the American colonies slower, greater disease in the American colonies Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 6 5/21/2014 8:00 PM

Chapter 05 Reading Questions Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Chapter 5 Reading Quiz Question 1 Part A In the second stage of the demographic transition, called the mortality transition, the death rate _____ while the birth rate _____. ANSWER: Chapter 5 Reading Quiz Question 2 Part A About a century ago, the population in Latin America moved from an agricultural to an urban-industrial base. During this period birth rates _____, death rates _____, and the overall population _____. ANSWER: Chapter 5 Reading Quiz Question 16 Part A Over the course of human history, the greatest increases in human populations have been due to_____. ANSWER: increases, decreases decreases, decreases decreases, remains high or increases increases, remains high or increases stayed about the same, decreased, and the population grew even faster increased greatly, increased, declined decreased dramatically, decreased, declined stayed about the same, increased, increased Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 4 Part A Compared to women in the United States, women in poor countries such as Ethiopia typically have _____ children at _____ age. ANSWER: Chapter 5 Reading Quiz Question 18 Part A Women in two developed countries have similar total fertility rates of 3.5. However, women in country A typically have their children about 2 years earlier than women in country B. How will the populations of the two countries compare? ANSWER: Chapter 5 Reading Quiz Question 19 Part A Overall population growth rates are most likely to be highest when the median age of a population is _____ and a country is in stage _____ of the demographic transition. ANSWER: improved medicine improved water supplies discovery of new land increased food production fewer, an older more, a younger more, an older fewer, a younger The population of country B will increase faster than country A. The population of country A will increase but the population of country B will decline. The population of country A will increase faster than country B. The populations of both countries will be stable, with similar totals and little increase or decrease. Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 20 Part A An age-structure diagram of a poor country in stage 1 of the demographic transition will be closest to the shape of _____. ANSWER: Chapter 5 Reading Quiz Question 8 Part A Predictions about global growth rates have been difficult because of changes in human values and behavior largely based upon _____. ANSWER: Chapter 5 Reading Quiz Question 9 Part A Because human suffering _____ as the human population approaches its carrying capacity, sustainability of the global human population must be _____ the carrying capacity of the Earth. ANSWER: older, 1 younger, 4 older, 3 younger, 2 the letter O, widest in the middle a pyramid, with a broad base and narrow top the letter V, widest at the top column, with even width from top to bottom shifting weather patterns increasing abilities to travel between countries the spread of infectious disease economic development Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 10 Part A The IPAT formula is used to estimate the _____. ANSWER: Chapter 5 Reading Quiz Question 12 Part A If everyone in the world had the ecological footprint of people currently living in the United States and Canada, the world would _____. ANSWER: Chapter 5 Reading Quiz Question 22 Part A If the population of the United States continues to grow and consumption levels also increase, we expect that the _____. ANSWER: increases, below decreases, above increases, above decreases, below birth rate of a population shift from one stage to another in the demographic transition age structure of a population ecological footprint of a society have just enough biocapacity without any additional population growth exceed its biocapacity by 40% still have enough biocapacity for 20% more humans exceed its biocapacity by five times over Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 24 Part A Given the increasing global population and increased rates of consumption in developing countries, the most likely avenue to sustainability is _____. ANSWER: Chapter 5 Reading Quiz Question 13 Part A Which one of the following typically contributes to population growth? ANSWER: Chapter 5 Reading Quiz Question 14 Part A Members of the neo-Malthusian movement advocated for _____. ANSWER: ecological footprint will eventually exceed the biocapacity of the environment biocapacity will eventually exceed the ecological footprint of the environment United States will eventually become an ecological debtor ecological debt of the United States will continue to increase more efficient use of natural resources the discovery of ways to dramatically increase the global biocapacity to have developed countries use more natural resources from developing countries increase our reliance upon fossil fuels better education empowerment of women high infant mortality economic development Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 6 5/21/2014 8:00 PM Chapter 5 Reading Quiz Question 15 Part A China, Mexico, and India have all made progress in reducing the population growth rates in their countries by adopting policies that encourage _____. ANSWER: Chapter 5 Reading Quiz Question 7 Part A Malthus found that populations in the American colonies were increasing _____ than populations on the European continent due to _____. ANSWER: Score Summary: Your score on this assignment is 0.0%. You received 0 out of a possible total of 17 points. increasing population size to support greater economic development birth control to limit population growth greater use of natural resources to increase the biocapacity of Earth to support a growing human population greater conservation of natural resources to limit the environmental impact of a growing human population limits on family size women to work only inside of their homes women to start having children at a younger age couples to marry earlier faster, no political conflicts or wars faster, greater resources were available in the American colonies slower, fewer resources were available in the American colonies slower, greater disease in the American colonies Chapter 05 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 6 5/21/2014 8:00 PM

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