1-Two notions serve as the basis for all torts: wrongs and compensation. True False 2-The goal of tort law is to put a defendant in the position that he or she would have been in had the tort occurred to the defendant. True False 3-Hayley is injured in an accident precipitated by Isolde. Hayley files a tort action against Isolde, seeking to recover for the damage suffered. Damages that are intended to compensate or reimburse a plaintiff for actual losses are: compensatory damages. reimbursement damages. actual damages. punitive damages. 4-Ladd throws a rock intending to hit Minh but misses and hits Nasir instead. On the basis of the tort of battery, Nasir can sue: Ladd. Minh. the rightful owner of the rock. no one. 4-Luella trespasses on Merchandise Mart’s property. Through the use of reasonable force, Merchandise Mart’s security guard detains Luella until the police arrive. Merchandise Mart is liable for: assault. battery. false imprisonment. none of the choice 6-The extreme risk of an activity is a defense against imposing strict liability. True False 7-Misrepresentation in an ad is enough to show an intent to induce the reliance of anyone who may use the product. True False 8-Luke is playing a video game on a defective disk that melts in his game player, starting a fire that injures his hands. Luke files a suit against Mystic Maze, Inc., the game’s maker under the doctrine of strict liability. A significant application of this doctrine is in the area of: cyber torts. intentional torts. product liability. unintentional torts 9-More than two hundred years ago, the Declaration of Independence recognized the importance of protecting creative works. True False 10-n 2014, Cloud Computing Corporation registers its trademark as provided by federal law. After the first renewal, this registration: is renewable every ten years. is renewable every twenty years. runs for life of the corporation plus seventy years. runs forever. 11-Wendy works as a weather announcer for a TV station under the character name Weather Wendy. Wendy can register her character’s name as: a certification mark. a trade name. a service mark. none of the choices 12-Much of the material on the Internet, including software and database information, is not copyrighted. True False 13-In a criminal case, the state must prove its case by a preponderance of the evidence. True False 14-Under the Fourth Amendmentt, general searches through a person’s belongings are permissible. True False 15-Maura enters a gas station and points a gun at the clerk Nate. She then forces Nate to open the cash register and give her all the money. Maura can be charged with: burglary. robbery. larceny. receiving stolen property. 16-Reno, driving while intoxicated, causes a car accident that results in the death of Santo. Reno is arrested and charged with a felony. A felony is a crime punishable by death or imprisonment for: any period of time. more than one year. more than six months. more than ten days. 17-Corporate officers and directors may be held criminally liable for the actions of employees under their supervision. True False 18-Sal assures Tom that she will deliver a truckload of hay to his cattle ranch. A person’s declaration to do a certain act is part of the definition of: an expectation. a moral obligation. a prediction. a promise. 19-Lark promises to buy Mac’s used textbook for $60. Lark is: an offeror. an offeree a promisee. a promisor. 20-Casey offers to sell a certain used forklift to DIY Lumber Outlet, but Casey dies before DIY accepts. Most likely, Casey’s death: did not affect the offer. shortened the time of the offer but did not terminated it. extended the time of the offer. terminated the offer.

1-Two notions serve as the basis for all torts: wrongs and compensation. True False 2-The goal of tort law is to put a defendant in the position that he or she would have been in had the tort occurred to the defendant. True False 3-Hayley is injured in an accident precipitated by Isolde. Hayley files a tort action against Isolde, seeking to recover for the damage suffered. Damages that are intended to compensate or reimburse a plaintiff for actual losses are: compensatory damages. reimbursement damages. actual damages. punitive damages. 4-Ladd throws a rock intending to hit Minh but misses and hits Nasir instead. On the basis of the tort of battery, Nasir can sue: Ladd. Minh. the rightful owner of the rock. no one. 4-Luella trespasses on Merchandise Mart’s property. Through the use of reasonable force, Merchandise Mart’s security guard detains Luella until the police arrive. Merchandise Mart is liable for: assault. battery. false imprisonment. none of the choice 6-The extreme risk of an activity is a defense against imposing strict liability. True False 7-Misrepresentation in an ad is enough to show an intent to induce the reliance of anyone who may use the product. True False 8-Luke is playing a video game on a defective disk that melts in his game player, starting a fire that injures his hands. Luke files a suit against Mystic Maze, Inc., the game’s maker under the doctrine of strict liability. A significant application of this doctrine is in the area of: cyber torts. intentional torts. product liability. unintentional torts 9-More than two hundred years ago, the Declaration of Independence recognized the importance of protecting creative works. True False 10-n 2014, Cloud Computing Corporation registers its trademark as provided by federal law. After the first renewal, this registration: is renewable every ten years. is renewable every twenty years. runs for life of the corporation plus seventy years. runs forever. 11-Wendy works as a weather announcer for a TV station under the character name Weather Wendy. Wendy can register her character’s name as: a certification mark. a trade name. a service mark. none of the choices 12-Much of the material on the Internet, including software and database information, is not copyrighted. True False 13-In a criminal case, the state must prove its case by a preponderance of the evidence. True False 14-Under the Fourth Amendmentt, general searches through a person’s belongings are permissible. True False 15-Maura enters a gas station and points a gun at the clerk Nate. She then forces Nate to open the cash register and give her all the money. Maura can be charged with: burglary. robbery. larceny. receiving stolen property. 16-Reno, driving while intoxicated, causes a car accident that results in the death of Santo. Reno is arrested and charged with a felony. A felony is a crime punishable by death or imprisonment for: any period of time. more than one year. more than six months. more than ten days. 17-Corporate officers and directors may be held criminally liable for the actions of employees under their supervision. True False 18-Sal assures Tom that she will deliver a truckload of hay to his cattle ranch. A person’s declaration to do a certain act is part of the definition of: an expectation. a moral obligation. a prediction. a promise. 19-Lark promises to buy Mac’s used textbook for $60. Lark is: an offeror. an offeree a promisee. a promisor. 20-Casey offers to sell a certain used forklift to DIY Lumber Outlet, but Casey dies before DIY accepts. Most likely, Casey’s death: did not affect the offer. shortened the time of the offer but did not terminated it. extended the time of the offer. terminated the offer.

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Chapter 9 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 Momentum and Internal Forces Learning Goal: To understand the concept of total momentum for a system of objects and the effect of the internal forces on the total momentum. We begin by introducing the following terms: System: Any collection of objects, either pointlike or extended. In many momentum-related problems, you have a certain freedom in choosing the objects to be considered as your system. Making a wise choice is often a crucial step in solving the problem. Internal force: Any force interaction between two objects belonging to the chosen system. Let us stress that both interacting objects must belong to the system. External force: Any force interaction between objects at least one of which does not belong to the chosen system; in other words, at least one of the objects is external to the system. Closed system: a system that is not subject to any external forces. Total momentum: The vector sum of the individual momenta of all objects constituting the system. In this problem, you will analyze a system composed of two blocks, 1 and 2, of respective masses and . To simplify the analysis, we will make several assumptions: The blocks can move in only one dimension, namely, 1. along the x axis. 2. The masses of the blocks remain constant. 3. The system is closed. At time , the x components of the velocity and the acceleration of block 1 are denoted by and . Similarly, the x components of the velocity and acceleration of block 2 are denoted by and . In this problem, you will show that the total momentum of the system is not changed by the presence of internal forces. m1 m2 t v1(t) a1 (t) v2 (t) a2 (t) Part A Find , the x component of the total momentum of the system at time . Express your answer in terms of , , , and . ANSWER: Part B Find the time derivative of the x component of the system’s total momentum. Express your answer in terms of , , , and . You did not open hints for this part. ANSWER: Why did we bother with all this math? The expression for the derivative of momentum that we just obtained will be useful in reaching our desired conclusion, if only for this very special case. Part C The quantity (mass times acceleration) is dimensionally equivalent to which of the following? ANSWER: p(t) t m1 m2 v1 (t) v2 (t) p(t) = dp(t)/dt a1 (t) a2 (t) m1 m2 dp(t)/dt = ma Part D Acceleration is due to which of the following physical quantities? ANSWER: Part E Since we have assumed that the system composed of blocks 1 and 2 is closed, what could be the reason for the acceleration of block 1? You did not open hints for this part. ANSWER: momentum energy force acceleration inertia velocity speed energy momentum force Part F This question will be shown after you complete previous question(s). Part G Let us denote the x component of the force exerted by block 1 on block 2 by , and the x component of the force exerted by block 2 on block 1 by . Which of the following pairs equalities is a direct consequence of Newton’s second law? ANSWER: Part H Let us recall that we have denoted the force exerted by block 1 on block 2 by , and the force exerted by block 2 on block 1 by . If we suppose that is greater than , which of the following statements about forces is true? You did not open hints for this part. the large mass of block 1 air resistance Earth’s gravitational attraction a force exerted by block 2 on block 1 a force exerted by block 1 on block 2 F12 F21 and and and and F12 = m2a2 F21 = m1a1 F12 = m1a1 F21 = m2a2 F12 = m1a2 F21 = m2a1 F12 = m2a1 F21 = m1a2 F12 F21 m1 m2 ANSWER: Part I Now recall the expression for the time derivative of the x component of the system’s total momentum: . Considering the information that you now have, choose the best alternative for an equivalent expression to . You did not open hints for this part. ANSWER: Impulse and Momentum Ranking Task Six automobiles are initially traveling at the indicated velocities. The automobiles have different masses and velocities. The drivers step on the brakes and all automobiles are brought to rest. Part A Rank these automobiles based on the magnitude of their momentum before the brakes are applied, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. ANSWER: Both forces have equal magnitudes. |F12 | > |F21| |F21 | > |F12| dpx(t)/dt = Fx dpx(t)/dt 0 nonzero constant kt kt2 Part B Rank these automobiles based on the magnitude of the impulse needed to stop them, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. You did not open hints for this part. ANSWER: Part C Rank the automobiles based on the magnitude of the force needed to stop them, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. You did not open hints for this part. ANSWER: A Game of Frictionless Catch Chuck and Jackie stand on separate carts, both of which can slide without friction. The combined mass of Chuck and his cart, , is identical to the combined mass of Jackie and her cart. Initially, Chuck and Jackie and their carts are at rest. Chuck then picks up a ball of mass and throws it to Jackie, who catches it. Assume that the ball travels in a straight line parallel to the ground (ignore the effect of gravity). After Chuck throws the ball, his speed relative to the ground is . The speed of the thrown ball relative to the ground is . Jackie catches the ball when it reaches her, and she and her cart begin to move. Jackie’s speed relative to the ground after she catches the ball is . When answering the questions in this problem, keep the following in mind: The original mass of Chuck and his cart does not include the 1. mass of the ball. 2. The speed of an object is the magnitude of its velocity. An object’s speed will always be a nonnegative quantity. mcart mball vc vb vj mcart Part A Find the relative speed between Chuck and the ball after Chuck has thrown the ball. Express the speed in terms of and . You did not open hints for this part. ANSWER: Part B What is the speed of the ball (relative to the ground) while it is in the air? Express your answer in terms of , , and . You did not open hints for this part. ANSWER: Part C What is Chuck’s speed (relative to the ground) after he throws the ball? Express your answer in terms of , , and . u vc vb u = vb mball mcart u vb = vc mball mcart u You did not open hints for this part. ANSWER: Part D Find Jackie’s speed (relative to the ground) after she catches the ball, in terms of . Express in terms of , , and . You did not open hints for this part. ANSWER: Part E Find Jackie’s speed (relative to the ground) after she catches the ball, in terms of . Express in terms of , , and . You did not open hints for this part. ANSWER: vc = vj vb vj mball mcart vb vj = vj u vj mball mcart u Momentum in an Explosion A giant “egg” explodes as part of a fireworks display. The egg is at rest before the explosion, and after the explosion, it breaks into two pieces, with the masses indicated in the diagram, traveling in opposite directions. Part A What is the momentum of piece A before the explosion? Express your answer numerically in kilogram meters per second. You did not open hints for this part. ANSWER: vj = pA,i Part B During the explosion, is the force of piece A on piece B greater than, less than, or equal to the force of piece B on piece A? You did not open hints for this part. ANSWER: Part C The momentum of piece B is measured to be 500 after the explosion. Find the momentum of piece A after the explosion. Enter your answer numerically in kilogram meters per second. You did not open hints for this part. ANSWER: pA,i = kg  m/s greater than less than equal to cannot be determined kg  m/s pA,f pA,f = kg  m/s ± PSS 9.1 Conservation of Momentum Learning Goal: To practice Problem-Solving Strategy 9.1 for conservation of momentum problems. An 80- quarterback jumps straight up in the air right before throwing a 0.43- football horizontally at 15 . How fast will he be moving backward just after releasing the ball? PROBLEM-SOLVING STRATEGY 9.1 Conservation of momentum MODEL: Clearly define the system. If possible, choose a system that is isolated ( ) or within which the interactions are sufficiently short and intense that you can ignore external forces for the duration of the interaction (the impulse approximation). Momentum is conserved. If it is not possible to choose an isolated system, try to divide the problem into parts such that momentum is conserved during one segment of the motion. Other segments of the motion can be analyzed using Newton’s laws or, as you will learn later, conservation of energy. VISUALIZE: Draw a before-and-after pictorial representation. Define symbols that will be used in the problem, list known values, and identify what you are trying to find. SOLVE: The mathematical representation is based on the law of conservation of momentum: . In component form, this is ASSESS: Check that your result has the correct units, is reasonable, and answers the question. Model The interaction at study in this problem is the action of throwing the ball, performed by the quarterback while being off the ground. To apply conservation of momentum to this interaction, you will need to clearly define a system that is isolated or within which the impulse approximation can be applied. Part A Sort the following objects as part of the system or not. Drag the appropriate objects to their respective bins. ANSWER: kg kg m/s F = net 0 P = f P  i (pfx + ( + ( += ( + ( + ( + )1 pfx)2 pfx)3 pix)1 pix)2 pix)3 (pfy + ( + ( += ( + ( + ( + )1 pfy)2 pfy)3 piy)1 piy)2 piy)3 Part B This question will be shown after you complete previous question(s). Visualize Solve Part C This question will be shown after you complete previous question(s). Assess Part D This question will be shown after you complete previous question(s). Conservation of Momentum in Inelastic Collisions Learning Goal: To understand the vector nature of momentum in the case in which two objects collide and stick together. In this problem we will consider a collision of two moving objects such that after the collision, the objects stick together and travel off as a single unit. The collision is therefore completely inelastic. You have probably learned that “momentum is conserved” in an inelastic collision. But how does this fact help you to solve collision problems? The following questions should help you to clarify the meaning and implications of the statement “momentum is conserved.” Part A What physical quantities are conserved in this collision? ANSWER: Part B Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are and . What is the speed of the two-car system after the collision? the magnitude of the momentum only the net momentum (considered as a vector) only the momentum of each object considered individually v1 v2 You did not open hints for this part. ANSWER: Part C Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are and . After the collision, what is the magnitude of their combined momentum? You did not open hints for this part. ANSWER: The answer depends on the directions in which the cars were moving before the collision. v1 + v2 v1 − v2 v2 − v1 v1v2 −−−− ” v1+v2 2 v1 + 2 v2 2 −−−−−−−  p1 p2 Part D Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are and . After the collision, their combined momentum is . Of what can one be certain? You did not open hints for this part. ANSWER: Part E Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are and . After the collision, the magnitude of their combined momentum is . Of what can one be certain? The answer depends on the directions in which the cars were moving before the collision. p1 + p2 p1 − p2 p2 − p1 p1p2 −−−− ” p1+p2 2 p1 + 2 p2 2 −−−−−−−  p 1 p 2 p p = p1 + # p2 # p = p1 − # p2 # p = p2 − # p1 # p1 p2 p You did not open hints for this part. ANSWER: Colliding Cars In this problem we will consider the collision of two cars initially moving at right angles. We assume that after the collision the cars stick together and travel off as a single unit. The collision is therefore completely inelastic. Two cars of masses and collide at an intersection. Before the collision, car 1 was traveling eastward at a speed of , and car 2 was traveling northward at a speed of . After the collision, the two cars stick together and travel off in the direction shown. Part A p1 + p2 $ p $ p1p2 −−−− ” p1 +p2 $ p $ p1+p2 2 p1 + p2 $ p $ |p1 − p2 | p1 + p2 $ p $ p1 + 2 p2 2 −−−−−−−  m1 m2 v1 v2 First, find the magnitude of , that is, the speed of the two-car unit after the collision. Express in terms of , , and the cars’ initial speeds and . You did not open hints for this part. ANSWER: Part B Find the tangent of the angle . Express your answer in terms of the momenta of the two cars, and . ANSWER: Part C Suppose that after the collision, ; in other words, is . This means that before the collision: ANSWER: v v v m1 m2 v1 v2 v = p1 p2 tan( ) = tan = 1 45′ The magnitudes of the momenta of the cars were equal. The masses of the cars were equal. The velocities of the cars were equal. ± Catching a Ball on Ice Olaf is standing on a sheet of ice that covers the football stadium parking lot in Buffalo, New York; there is negligible friction between his feet and the ice. A friend throws Olaf a ball of mass 0.400 that is traveling horizontally at 11.2 . Olaf’s mass is 67.1 . Part A If Olaf catches the ball, with what speed do Olaf and the ball move afterward? Express your answer numerically in meters per second. You did not open hints for this part. ANSWER: Part B kg m/s kg vf vf = m/s If the ball hits Olaf and bounces off his chest horizontally at 8.00 in the opposite direction, what is his speed after the collision? Express your answer numerically in meters per second. You did not open hints for this part. ANSWER: A One-Dimensional Inelastic Collision Block 1, of mass = 2.90 , moves along a frictionless air track with speed = 25.0 . It collides with block 2, of mass = 17.0 , which was initially at rest. The blocks stick together after the collision. Part A Find the magnitude of the total initial momentum of the two-block system. Express your answer numerically. m/s vf vf = m/s m1 kg v1 m/s m2 kg pi You did not open hints for this part. ANSWER: Part B Find , the magnitude of the final velocity of the two-block system. Express your answer numerically. You did not open hints for this part. ANSWER: Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. pi = kg  m/s vf vf = m/s

Chapter 9 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 Momentum and Internal Forces Learning Goal: To understand the concept of total momentum for a system of objects and the effect of the internal forces on the total momentum. We begin by introducing the following terms: System: Any collection of objects, either pointlike or extended. In many momentum-related problems, you have a certain freedom in choosing the objects to be considered as your system. Making a wise choice is often a crucial step in solving the problem. Internal force: Any force interaction between two objects belonging to the chosen system. Let us stress that both interacting objects must belong to the system. External force: Any force interaction between objects at least one of which does not belong to the chosen system; in other words, at least one of the objects is external to the system. Closed system: a system that is not subject to any external forces. Total momentum: The vector sum of the individual momenta of all objects constituting the system. In this problem, you will analyze a system composed of two blocks, 1 and 2, of respective masses and . To simplify the analysis, we will make several assumptions: The blocks can move in only one dimension, namely, 1. along the x axis. 2. The masses of the blocks remain constant. 3. The system is closed. At time , the x components of the velocity and the acceleration of block 1 are denoted by and . Similarly, the x components of the velocity and acceleration of block 2 are denoted by and . In this problem, you will show that the total momentum of the system is not changed by the presence of internal forces. m1 m2 t v1(t) a1 (t) v2 (t) a2 (t) Part A Find , the x component of the total momentum of the system at time . Express your answer in terms of , , , and . ANSWER: Part B Find the time derivative of the x component of the system’s total momentum. Express your answer in terms of , , , and . You did not open hints for this part. ANSWER: Why did we bother with all this math? The expression for the derivative of momentum that we just obtained will be useful in reaching our desired conclusion, if only for this very special case. Part C The quantity (mass times acceleration) is dimensionally equivalent to which of the following? ANSWER: p(t) t m1 m2 v1 (t) v2 (t) p(t) = dp(t)/dt a1 (t) a2 (t) m1 m2 dp(t)/dt = ma Part D Acceleration is due to which of the following physical quantities? ANSWER: Part E Since we have assumed that the system composed of blocks 1 and 2 is closed, what could be the reason for the acceleration of block 1? You did not open hints for this part. ANSWER: momentum energy force acceleration inertia velocity speed energy momentum force Part F This question will be shown after you complete previous question(s). Part G Let us denote the x component of the force exerted by block 1 on block 2 by , and the x component of the force exerted by block 2 on block 1 by . Which of the following pairs equalities is a direct consequence of Newton’s second law? ANSWER: Part H Let us recall that we have denoted the force exerted by block 1 on block 2 by , and the force exerted by block 2 on block 1 by . If we suppose that is greater than , which of the following statements about forces is true? You did not open hints for this part. the large mass of block 1 air resistance Earth’s gravitational attraction a force exerted by block 2 on block 1 a force exerted by block 1 on block 2 F12 F21 and and and and F12 = m2a2 F21 = m1a1 F12 = m1a1 F21 = m2a2 F12 = m1a2 F21 = m2a1 F12 = m2a1 F21 = m1a2 F12 F21 m1 m2 ANSWER: Part I Now recall the expression for the time derivative of the x component of the system’s total momentum: . Considering the information that you now have, choose the best alternative for an equivalent expression to . You did not open hints for this part. ANSWER: Impulse and Momentum Ranking Task Six automobiles are initially traveling at the indicated velocities. The automobiles have different masses and velocities. The drivers step on the brakes and all automobiles are brought to rest. Part A Rank these automobiles based on the magnitude of their momentum before the brakes are applied, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. ANSWER: Both forces have equal magnitudes. |F12 | > |F21| |F21 | > |F12| dpx(t)/dt = Fx dpx(t)/dt 0 nonzero constant kt kt2 Part B Rank these automobiles based on the magnitude of the impulse needed to stop them, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. You did not open hints for this part. ANSWER: Part C Rank the automobiles based on the magnitude of the force needed to stop them, from largest to smallest. Rank from largest to smallest. To rank items as equivalent, overlap them. If the ranking cannot be determined, check the box below. You did not open hints for this part. ANSWER: A Game of Frictionless Catch Chuck and Jackie stand on separate carts, both of which can slide without friction. The combined mass of Chuck and his cart, , is identical to the combined mass of Jackie and her cart. Initially, Chuck and Jackie and their carts are at rest. Chuck then picks up a ball of mass and throws it to Jackie, who catches it. Assume that the ball travels in a straight line parallel to the ground (ignore the effect of gravity). After Chuck throws the ball, his speed relative to the ground is . The speed of the thrown ball relative to the ground is . Jackie catches the ball when it reaches her, and she and her cart begin to move. Jackie’s speed relative to the ground after she catches the ball is . When answering the questions in this problem, keep the following in mind: The original mass of Chuck and his cart does not include the 1. mass of the ball. 2. The speed of an object is the magnitude of its velocity. An object’s speed will always be a nonnegative quantity. mcart mball vc vb vj mcart Part A Find the relative speed between Chuck and the ball after Chuck has thrown the ball. Express the speed in terms of and . You did not open hints for this part. ANSWER: Part B What is the speed of the ball (relative to the ground) while it is in the air? Express your answer in terms of , , and . You did not open hints for this part. ANSWER: Part C What is Chuck’s speed (relative to the ground) after he throws the ball? Express your answer in terms of , , and . u vc vb u = vb mball mcart u vb = vc mball mcart u You did not open hints for this part. ANSWER: Part D Find Jackie’s speed (relative to the ground) after she catches the ball, in terms of . Express in terms of , , and . You did not open hints for this part. ANSWER: Part E Find Jackie’s speed (relative to the ground) after she catches the ball, in terms of . Express in terms of , , and . You did not open hints for this part. ANSWER: vc = vj vb vj mball mcart vb vj = vj u vj mball mcart u Momentum in an Explosion A giant “egg” explodes as part of a fireworks display. The egg is at rest before the explosion, and after the explosion, it breaks into two pieces, with the masses indicated in the diagram, traveling in opposite directions. Part A What is the momentum of piece A before the explosion? Express your answer numerically in kilogram meters per second. You did not open hints for this part. ANSWER: vj = pA,i Part B During the explosion, is the force of piece A on piece B greater than, less than, or equal to the force of piece B on piece A? You did not open hints for this part. ANSWER: Part C The momentum of piece B is measured to be 500 after the explosion. Find the momentum of piece A after the explosion. Enter your answer numerically in kilogram meters per second. You did not open hints for this part. ANSWER: pA,i = kg  m/s greater than less than equal to cannot be determined kg  m/s pA,f pA,f = kg  m/s ± PSS 9.1 Conservation of Momentum Learning Goal: To practice Problem-Solving Strategy 9.1 for conservation of momentum problems. An 80- quarterback jumps straight up in the air right before throwing a 0.43- football horizontally at 15 . How fast will he be moving backward just after releasing the ball? PROBLEM-SOLVING STRATEGY 9.1 Conservation of momentum MODEL: Clearly define the system. If possible, choose a system that is isolated ( ) or within which the interactions are sufficiently short and intense that you can ignore external forces for the duration of the interaction (the impulse approximation). Momentum is conserved. If it is not possible to choose an isolated system, try to divide the problem into parts such that momentum is conserved during one segment of the motion. Other segments of the motion can be analyzed using Newton’s laws or, as you will learn later, conservation of energy. VISUALIZE: Draw a before-and-after pictorial representation. Define symbols that will be used in the problem, list known values, and identify what you are trying to find. SOLVE: The mathematical representation is based on the law of conservation of momentum: . In component form, this is ASSESS: Check that your result has the correct units, is reasonable, and answers the question. Model The interaction at study in this problem is the action of throwing the ball, performed by the quarterback while being off the ground. To apply conservation of momentum to this interaction, you will need to clearly define a system that is isolated or within which the impulse approximation can be applied. Part A Sort the following objects as part of the system or not. Drag the appropriate objects to their respective bins. ANSWER: kg kg m/s F = net 0 P = f P  i (pfx + ( + ( += ( + ( + ( + )1 pfx)2 pfx)3 pix)1 pix)2 pix)3 (pfy + ( + ( += ( + ( + ( + )1 pfy)2 pfy)3 piy)1 piy)2 piy)3 Part B This question will be shown after you complete previous question(s). Visualize Solve Part C This question will be shown after you complete previous question(s). Assess Part D This question will be shown after you complete previous question(s). Conservation of Momentum in Inelastic Collisions Learning Goal: To understand the vector nature of momentum in the case in which two objects collide and stick together. In this problem we will consider a collision of two moving objects such that after the collision, the objects stick together and travel off as a single unit. The collision is therefore completely inelastic. You have probably learned that “momentum is conserved” in an inelastic collision. But how does this fact help you to solve collision problems? The following questions should help you to clarify the meaning and implications of the statement “momentum is conserved.” Part A What physical quantities are conserved in this collision? ANSWER: Part B Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are and . What is the speed of the two-car system after the collision? the magnitude of the momentum only the net momentum (considered as a vector) only the momentum of each object considered individually v1 v2 You did not open hints for this part. ANSWER: Part C Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are and . After the collision, what is the magnitude of their combined momentum? You did not open hints for this part. ANSWER: The answer depends on the directions in which the cars were moving before the collision. v1 + v2 v1 − v2 v2 − v1 v1v2 −−−− ” v1+v2 2 v1 + 2 v2 2 −−−−−−−  p1 p2 Part D Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are and . After the collision, their combined momentum is . Of what can one be certain? You did not open hints for this part. ANSWER: Part E Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are and . After the collision, the magnitude of their combined momentum is . Of what can one be certain? The answer depends on the directions in which the cars were moving before the collision. p1 + p2 p1 − p2 p2 − p1 p1p2 −−−− ” p1+p2 2 p1 + 2 p2 2 −−−−−−−  p 1 p 2 p p = p1 + # p2 # p = p1 − # p2 # p = p2 − # p1 # p1 p2 p You did not open hints for this part. ANSWER: Colliding Cars In this problem we will consider the collision of two cars initially moving at right angles. We assume that after the collision the cars stick together and travel off as a single unit. The collision is therefore completely inelastic. Two cars of masses and collide at an intersection. Before the collision, car 1 was traveling eastward at a speed of , and car 2 was traveling northward at a speed of . After the collision, the two cars stick together and travel off in the direction shown. Part A p1 + p2 $ p $ p1p2 −−−− ” p1 +p2 $ p $ p1+p2 2 p1 + p2 $ p $ |p1 − p2 | p1 + p2 $ p $ p1 + 2 p2 2 −−−−−−−  m1 m2 v1 v2 First, find the magnitude of , that is, the speed of the two-car unit after the collision. Express in terms of , , and the cars’ initial speeds and . You did not open hints for this part. ANSWER: Part B Find the tangent of the angle . Express your answer in terms of the momenta of the two cars, and . ANSWER: Part C Suppose that after the collision, ; in other words, is . This means that before the collision: ANSWER: v v v m1 m2 v1 v2 v = p1 p2 tan( ) = tan = 1 45′ The magnitudes of the momenta of the cars were equal. The masses of the cars were equal. The velocities of the cars were equal. ± Catching a Ball on Ice Olaf is standing on a sheet of ice that covers the football stadium parking lot in Buffalo, New York; there is negligible friction between his feet and the ice. A friend throws Olaf a ball of mass 0.400 that is traveling horizontally at 11.2 . Olaf’s mass is 67.1 . Part A If Olaf catches the ball, with what speed do Olaf and the ball move afterward? Express your answer numerically in meters per second. You did not open hints for this part. ANSWER: Part B kg m/s kg vf vf = m/s If the ball hits Olaf and bounces off his chest horizontally at 8.00 in the opposite direction, what is his speed after the collision? Express your answer numerically in meters per second. You did not open hints for this part. ANSWER: A One-Dimensional Inelastic Collision Block 1, of mass = 2.90 , moves along a frictionless air track with speed = 25.0 . It collides with block 2, of mass = 17.0 , which was initially at rest. The blocks stick together after the collision. Part A Find the magnitude of the total initial momentum of the two-block system. Express your answer numerically. m/s vf vf = m/s m1 kg v1 m/s m2 kg pi You did not open hints for this part. ANSWER: Part B Find , the magnitude of the final velocity of the two-block system. Express your answer numerically. You did not open hints for this part. ANSWER: Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. pi = kg  m/s vf vf = m/s

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Learning Objectives This part begins with what are probably the basic questions for a designer of a computing sytem’s human interface: • How should the functionality of the system be described and presented to the user? • How can the design of the interface help the user to understand and successfully use the system? Learning Goals At the conclusion of this module you will be able to: • define the user’s movement among the displays that make up the system; • the addition of visual and spatial cues to the information organization; and • methods of structuring and presenting the interface. Introduction This module deals with the development and utilization of a system. We all have systems for doing things. For instance, we may have a system for handling routine situations around the house that makes sense only to us. Or, we may be oriented toward systems that have a more widespread understanding such as personal finance or how to fill out our IRS forms. When humans use a system, whether natural or man-made, they do so based on their understanding of that system. A totally accurate understanding of a system is not a necessary condition for effective use of that system. Key Terms Systems, User Model, Model, Metaphor, Concept Modeling The Development of Human Systems I. The organization of knowledge about a phenomenon or system constitutes the human’s conceptual model of that system. Information gained from experience with a system contributes to the model, and the model in turn provides a reference or guide for future experience with the system. A. (Reinstein and Hersh, 1984) – a set of concepts a person gradually acquires to explain the behavior of a system. …. That enables that person to understand and interact with the system. 1. For the user, the important thing about a model is its ability to predict: when confronted with unfamiliar or incompletely understood situations, the user relies on their model, their conceptual understanding of the system, to make educated guesses about how to proceed. If the user’s model accurately reflects the effects of the system, then he will be more successful in learning and using the system, and likely will perceive the system as easy to use. 2. Because the model can server this important role in design of helping to create an understandable and predictable system, the creation of the user’s conceptual model should be the first task of system development. One of the more important examples of the use of conceptual model, the XEROX Star office automation system (whose design greatly influenced Apple’s Lisa and Macintosh systems), started with thirty man-years of design work on the user interface before either the hardware or the system software was designed (Smith, Irby, Kimball, Verplank and Harselm, 1982). 3. The conceptual model does not have to be an accurate representation of how the system actually functions. Indeed, it can be quite different from reality, and in most if not all circumstances for systems as complex as computers, should be. 4. The model may be a myth or metaphor, that explains the system: it “suggests that the computer is like something with which the user is already familiar” (Rubinstein and Hersh, 1984, p. 43), or provides a simple explanation of the system which can be used to predict the system’s behavior. 5. ….the conceptual models people form are based on their interactions with an environment … “people who have different roles within an environment … will form different conceptual systems of those environments. 6. People whose essential interaction with an environment is to create it will almost inevitably have an understanding and conceptualization of it which is different from those whose major interaction with it is to use it” Action Assignment Based on the readings for this module, please identify a personal “system” with which you act and perform within. This should be from personal experience and one that assists in providing a model for organization, understanding and problem solving.

Learning Objectives This part begins with what are probably the basic questions for a designer of a computing sytem’s human interface: • How should the functionality of the system be described and presented to the user? • How can the design of the interface help the user to understand and successfully use the system? Learning Goals At the conclusion of this module you will be able to: • define the user’s movement among the displays that make up the system; • the addition of visual and spatial cues to the information organization; and • methods of structuring and presenting the interface. Introduction This module deals with the development and utilization of a system. We all have systems for doing things. For instance, we may have a system for handling routine situations around the house that makes sense only to us. Or, we may be oriented toward systems that have a more widespread understanding such as personal finance or how to fill out our IRS forms. When humans use a system, whether natural or man-made, they do so based on their understanding of that system. A totally accurate understanding of a system is not a necessary condition for effective use of that system. Key Terms Systems, User Model, Model, Metaphor, Concept Modeling The Development of Human Systems I. The organization of knowledge about a phenomenon or system constitutes the human’s conceptual model of that system. Information gained from experience with a system contributes to the model, and the model in turn provides a reference or guide for future experience with the system. A. (Reinstein and Hersh, 1984) – a set of concepts a person gradually acquires to explain the behavior of a system. …. That enables that person to understand and interact with the system. 1. For the user, the important thing about a model is its ability to predict: when confronted with unfamiliar or incompletely understood situations, the user relies on their model, their conceptual understanding of the system, to make educated guesses about how to proceed. If the user’s model accurately reflects the effects of the system, then he will be more successful in learning and using the system, and likely will perceive the system as easy to use. 2. Because the model can server this important role in design of helping to create an understandable and predictable system, the creation of the user’s conceptual model should be the first task of system development. One of the more important examples of the use of conceptual model, the XEROX Star office automation system (whose design greatly influenced Apple’s Lisa and Macintosh systems), started with thirty man-years of design work on the user interface before either the hardware or the system software was designed (Smith, Irby, Kimball, Verplank and Harselm, 1982). 3. The conceptual model does not have to be an accurate representation of how the system actually functions. Indeed, it can be quite different from reality, and in most if not all circumstances for systems as complex as computers, should be. 4. The model may be a myth or metaphor, that explains the system: it “suggests that the computer is like something with which the user is already familiar” (Rubinstein and Hersh, 1984, p. 43), or provides a simple explanation of the system which can be used to predict the system’s behavior. 5. ….the conceptual models people form are based on their interactions with an environment … “people who have different roles within an environment … will form different conceptual systems of those environments. 6. People whose essential interaction with an environment is to create it will almost inevitably have an understanding and conceptualization of it which is different from those whose major interaction with it is to use it” Action Assignment Based on the readings for this module, please identify a personal “system” with which you act and perform within. This should be from personal experience and one that assists in providing a model for organization, understanding and problem solving.

This assignment provides you the opportunity to reflect on the topics ethics and how one might experience ethical challenges early in one’s career. The attached scenario is based on actual events and used with permission of ASCE. Using the attached scenario and American Society of Civil Engineers (ASCE) code of ethics, develop a response to the questions that are included within the scenario. Your deliverable must be in the form of a memorandum, which could be used as a reference or guideline when discussing the importance of ethics colleagues. When answering the questions you should be specific in identifying the components of the code of ethics you use to reflect on the questions posed and how they would be used to assist someone facing the same scenario. Ethics Scenario and Questions: Last month, Sara was reported to her State’s Engineer’s Board for a possible ethics violation. Tomorrow morning she would meet with the Board and though she felt she had done nothing unethical, Sara’s eyes had been opened to the complexity and gravity of ethical dilemmas in engineering practice. She wished she had sought and/or received better guidance regarding ethical issues earlier in her career. Sara reflected on how she got to this point in her career. When Sara had been a senior Civil Engineering student in an ABET-accredited program at the State University, she immersed herself in her course work. Graduating at the top of her class assured Sara that she would have some choice in her career direction. Knowing that she wanted to become a licensed engineer, Sara took and passed the Fundamentals of Engineering (FE) exam during her senior year and after graduation, went to work as an Engineer Intern (EI) for a company that would allow her to achieve that goal. Sara was excited about her new job — she worked diligently for four years under licensed engineers and was assigned increasing responsibilities. She was now ready to take the Professional Engineer (PE) exam and become licensed. Just before taking the PE licensing exam, Sara’s firm was retained to investigate the structural integrity of an apartment complex that the firm’s client planned to sell. Sara’s supervisor informed her in no uncertain terms that the client required that the structural report remain confidential. Later, the client informed Sara that he planned to sell the occupied property “as is.” During Sara’s investigation she found no significant structural problems with the apartment complex. However, she did observe some electrical deficiencies that she believed violated city codes and could pose a safety hazard to the occupants. Realizing that electrical matters were, in a manner of speaking, not her direct area of expertise, Sara discussed possible approaches with her colleague and friend, Tom. Also an Engineer Intern, Tom had been an officer in the student chapter of ASCE during their college years. During their conversation, Tom commented that based on the ASCE Code of Ethics, he believed Sara had an ethical obligation to disclose this health-safety problem. Sara felt Tom did not appreciate the fact that she had been clearly instructed to keep such information confidential, and she certainly did not want to damage the client relationship. Nevertheless, with reluctance, Sara verbally informed the client about the problem and made an oblique reference to the electrical deficiencies in her report, which her supervisor signed and sealed. Several weeks later, Sara learned that her client did not inform either the residents of the apartment complex or the prospective buyer about her concerns. Although Sara felt confident and pleased with her work on the project, the situation about the electrical deficiencies continued to bother her. She wondered if she had an ethical obligation to do more than just tell the client and state her concerns in her report. The thought of informing the proper authorities occurred to her, especially since the client was not disclosing the potential safety concerns to either the occupants or the buyer. She toyed with the idea of discussing the situation with her immediate supervisor but since everyone seemed satisfied, Sara moved onto other projects and eventually put it out of her mind. Questions to consider (What were the main issues Sara was wrestling with in this situation? ; Do you think Sara had a “right” or an “obligation” to report the deficiency to the proper authorities? ;Who might Sara have spoken with about the dilemma? ; Who should be responsible for what happened – Sara, Sara’s employer, the client, or someone else? ; How does this situation conflict with Sara’s obligation to be faithful to her client? ; Is it wise practice to ignore “gut feelings” that arise? These and other questions will surface again later and most will be considered at that point, but let’s continue for now with Sara’s story. During her first few years with the company, and under the supervision of several managers, Sara was encouraged to become active in technical and professional societies (which was the policy of the company). But then she found her involvement with those groups diminishing as her current supervisor opposed Sara’s participation in meetings and conferences unless she used vacation time. Sara was very frustrated but did not really know how to rectify the situation. In the course of time, Sara attended a meeting with the CEO on a different matter and she took the opportunity to inquire about attending technical and professional society meetings. The CEO reaffirmed that the company thought it important and that he wanted Sara to participate in such meetings. Sara informed her supervisor and though he did begin approving Sara’s requests for leave to participate in society meetings, their relationship was strained. Questions to consider: What might Sara have done differently to seek a remedy and yet preserve her relationship with her supervisor? ; Where could Sara have found guidance in the ASCE Code of Ethics, appropriate to this situation? The story continues….. As Christmas approached the following year, Sara discovered a gift bag on her desk. Inside the gift bag was an expensive honey-glazed spiral cut ham and a Christmas greeting card from a vendor who called on Sara from time to time. This concerned Sara as she felt it might cast doubt on the integrity of their business relationship. She asked around and found that several others received gifts from the vendor as well. After sleeping on it, Sara sent a polite note to the vendor returning the ham. Questions to consider: Was Sara really obligated to return the ham? Or was this taking ethics too far? ; On the other hand, could Sara be obligated to pursue the matter further than just returning the gift she had received? A few years later, friends and colleagues urged Sara, now a highly successful principal in a respected engineering firm, to run for public office. Sara carefully considered this step, realizing it would be a challenge to juggle work, family, and such intense community involvement. Ultimately, she agreed to run and soon found herself immersed in the campaign. A draft political advertisement was prepared that included her photograph, her engineering seal, and the following text: “Vote for Sara! We need an engineer on the City Council. That is simple common sense, isn’t it? Sara is an experienced licensed engineer with years of rich accomplishments, who disdains delays and takes action now!” Questions to consider: Should Sara’s engineering seal be included in the advertisement? ; Should she ask someone in ASCE his or her opinion before deciding? As fate would have it, a few days later, just after announcing her candidacy for City Council, the matter of Sara’s investigation of the apartment complex so many years ago resurfaced. Sara learned that the apartment complex caught on fire, and people had been seriously injured. During the investigation of the cause of the fire, Sara’s report was reviewed, and somehow the cause of the fire was traced to the electrical deficiencies, which she had briefly mentioned. Immediately this hit the local newspapers, attorneys became involved, and subsequently the Licensing Board was asked to look into the ethical responsibilities related to the report. Now, sitting alone by the shore of the lake, Sara pondered her situation. Legally, she felt she might claim some immunity since she was not a licensed engineer at the time of her work on the apartment complex. But professionally, she keenly felt she had let the public down, and she could not get this, or those who had been hurt in the fire, out of her mind. Question to consider: Occasionally, are some elements of the code in conflict with other elements In the backseat of the taxi on the way to the airport, Sara thumbed through her hometown newspaper that she had purchased at a newsstand. She stopped when she saw an editorial about her City Council campaign. The article claimed that, as a result of the allegations against her, she was no longer fit for public office. Could this be true? Question to consider: How should she respond to such claims?

This assignment provides you the opportunity to reflect on the topics ethics and how one might experience ethical challenges early in one’s career. The attached scenario is based on actual events and used with permission of ASCE. Using the attached scenario and American Society of Civil Engineers (ASCE) code of ethics, develop a response to the questions that are included within the scenario. Your deliverable must be in the form of a memorandum, which could be used as a reference or guideline when discussing the importance of ethics colleagues. When answering the questions you should be specific in identifying the components of the code of ethics you use to reflect on the questions posed and how they would be used to assist someone facing the same scenario. Ethics Scenario and Questions: Last month, Sara was reported to her State’s Engineer’s Board for a possible ethics violation. Tomorrow morning she would meet with the Board and though she felt she had done nothing unethical, Sara’s eyes had been opened to the complexity and gravity of ethical dilemmas in engineering practice. She wished she had sought and/or received better guidance regarding ethical issues earlier in her career. Sara reflected on how she got to this point in her career. When Sara had been a senior Civil Engineering student in an ABET-accredited program at the State University, she immersed herself in her course work. Graduating at the top of her class assured Sara that she would have some choice in her career direction. Knowing that she wanted to become a licensed engineer, Sara took and passed the Fundamentals of Engineering (FE) exam during her senior year and after graduation, went to work as an Engineer Intern (EI) for a company that would allow her to achieve that goal. Sara was excited about her new job — she worked diligently for four years under licensed engineers and was assigned increasing responsibilities. She was now ready to take the Professional Engineer (PE) exam and become licensed. Just before taking the PE licensing exam, Sara’s firm was retained to investigate the structural integrity of an apartment complex that the firm’s client planned to sell. Sara’s supervisor informed her in no uncertain terms that the client required that the structural report remain confidential. Later, the client informed Sara that he planned to sell the occupied property “as is.” During Sara’s investigation she found no significant structural problems with the apartment complex. However, she did observe some electrical deficiencies that she believed violated city codes and could pose a safety hazard to the occupants. Realizing that electrical matters were, in a manner of speaking, not her direct area of expertise, Sara discussed possible approaches with her colleague and friend, Tom. Also an Engineer Intern, Tom had been an officer in the student chapter of ASCE during their college years. During their conversation, Tom commented that based on the ASCE Code of Ethics, he believed Sara had an ethical obligation to disclose this health-safety problem. Sara felt Tom did not appreciate the fact that she had been clearly instructed to keep such information confidential, and she certainly did not want to damage the client relationship. Nevertheless, with reluctance, Sara verbally informed the client about the problem and made an oblique reference to the electrical deficiencies in her report, which her supervisor signed and sealed. Several weeks later, Sara learned that her client did not inform either the residents of the apartment complex or the prospective buyer about her concerns. Although Sara felt confident and pleased with her work on the project, the situation about the electrical deficiencies continued to bother her. She wondered if she had an ethical obligation to do more than just tell the client and state her concerns in her report. The thought of informing the proper authorities occurred to her, especially since the client was not disclosing the potential safety concerns to either the occupants or the buyer. She toyed with the idea of discussing the situation with her immediate supervisor but since everyone seemed satisfied, Sara moved onto other projects and eventually put it out of her mind. Questions to consider (What were the main issues Sara was wrestling with in this situation? ; Do you think Sara had a “right” or an “obligation” to report the deficiency to the proper authorities? ;Who might Sara have spoken with about the dilemma? ; Who should be responsible for what happened – Sara, Sara’s employer, the client, or someone else? ; How does this situation conflict with Sara’s obligation to be faithful to her client? ; Is it wise practice to ignore “gut feelings” that arise? These and other questions will surface again later and most will be considered at that point, but let’s continue for now with Sara’s story. During her first few years with the company, and under the supervision of several managers, Sara was encouraged to become active in technical and professional societies (which was the policy of the company). But then she found her involvement with those groups diminishing as her current supervisor opposed Sara’s participation in meetings and conferences unless she used vacation time. Sara was very frustrated but did not really know how to rectify the situation. In the course of time, Sara attended a meeting with the CEO on a different matter and she took the opportunity to inquire about attending technical and professional society meetings. The CEO reaffirmed that the company thought it important and that he wanted Sara to participate in such meetings. Sara informed her supervisor and though he did begin approving Sara’s requests for leave to participate in society meetings, their relationship was strained. Questions to consider: What might Sara have done differently to seek a remedy and yet preserve her relationship with her supervisor? ; Where could Sara have found guidance in the ASCE Code of Ethics, appropriate to this situation? The story continues….. As Christmas approached the following year, Sara discovered a gift bag on her desk. Inside the gift bag was an expensive honey-glazed spiral cut ham and a Christmas greeting card from a vendor who called on Sara from time to time. This concerned Sara as she felt it might cast doubt on the integrity of their business relationship. She asked around and found that several others received gifts from the vendor as well. After sleeping on it, Sara sent a polite note to the vendor returning the ham. Questions to consider: Was Sara really obligated to return the ham? Or was this taking ethics too far? ; On the other hand, could Sara be obligated to pursue the matter further than just returning the gift she had received? A few years later, friends and colleagues urged Sara, now a highly successful principal in a respected engineering firm, to run for public office. Sara carefully considered this step, realizing it would be a challenge to juggle work, family, and such intense community involvement. Ultimately, she agreed to run and soon found herself immersed in the campaign. A draft political advertisement was prepared that included her photograph, her engineering seal, and the following text: “Vote for Sara! We need an engineer on the City Council. That is simple common sense, isn’t it? Sara is an experienced licensed engineer with years of rich accomplishments, who disdains delays and takes action now!” Questions to consider: Should Sara’s engineering seal be included in the advertisement? ; Should she ask someone in ASCE his or her opinion before deciding? As fate would have it, a few days later, just after announcing her candidacy for City Council, the matter of Sara’s investigation of the apartment complex so many years ago resurfaced. Sara learned that the apartment complex caught on fire, and people had been seriously injured. During the investigation of the cause of the fire, Sara’s report was reviewed, and somehow the cause of the fire was traced to the electrical deficiencies, which she had briefly mentioned. Immediately this hit the local newspapers, attorneys became involved, and subsequently the Licensing Board was asked to look into the ethical responsibilities related to the report. Now, sitting alone by the shore of the lake, Sara pondered her situation. Legally, she felt she might claim some immunity since she was not a licensed engineer at the time of her work on the apartment complex. But professionally, she keenly felt she had let the public down, and she could not get this, or those who had been hurt in the fire, out of her mind. Question to consider: Occasionally, are some elements of the code in conflict with other elements In the backseat of the taxi on the way to the airport, Sara thumbed through her hometown newspaper that she had purchased at a newsstand. She stopped when she saw an editorial about her City Council campaign. The article claimed that, as a result of the allegations against her, she was no longer fit for public office. Could this be true? Question to consider: How should she respond to such claims?

MEMO       To: Ms. Sara From: Ethics Monitoring … Read More...
English 1 Professor Nielsen Essay One Topic and Guidelines The Context You are a non-profit organization Director of Fundraising, and your goal is to convince a wealthy individual to make a substantial donation to your cause. Choose from one of the following projects derived from the social issues from the course readings below: 1. The Prison Project: Reducing the incarceration rate and numbers in the U.S. 2. Birth Control Advocacy and Access: Supporting a birth control education and free product distribution in the U.S and/or internationally. 3. LGBT Advocacy: Funding education, campaigning, and lobbying for LGBT rights in the U.S. 4. Equality in Education: Supporting funding and scholarships for schools and individuals from less advantaged populations. 5. Migrant Welfare and Protection: Creating safe housing, food, and education for refugees. 6. Something else related to social justice?????? (See me if you have your own project idea). (animal welfare, women’s advocacy, housing, student loans and tuition affordability, etc.) Make a case for a donation of $2 million dollars to your cause by writing a funding request letter to the potential donor. This request is essentially a persuasive essay designed to convince your reader to support your cause. Below is a suggested format for organizing your letter, as well as guidelines for your work. I. The Basics Due: Tuesday, September 29, at Start of Class (Rough Draft). And Tuesday, October 6, at Start of Class (Final Draft) Length: 3-4 Pgs., double spaced in the correct format (see sample paper format template at the end of this document for format.) Font: Times New Roman, 12PT. Margins: 1 inch all around. See sample format at the end of this document for further formatting information. You are required to submit using this format. Check the sample on page five of this document carefully. Editing: Be sure to use the proofreading guide. In particular, avoid the big five errors. Revising: Read over your draft carefully several times. We will work toward revision together in class, but you will also need to revise on your own. Visit the Learning center if you need extra support. II. Organization and Content (Sample Outline Follows.) Use an organized format for your essay. The best way to ensure strong organization is to map out a plan for the content of your essay, using an outline, clustering, or other graphic representation of your key ideas. One potential format follows. Sample Method of Organizing Your Funding Letter: A. The Opening Paragraph 1. Start with some brief striking details to provide the initial background to your letter: facts, figures, brief description of one aspect of the problem- something compelling. 2. End your paragraph with a statement that briefly announces/introduces your organization without yet going into detail about your mission. State that you are requesting a donation and that your letter will describe the need for this donation. (Your Thesis) B. Body of the Letter: The Problem Make a stronger case for the problem your organization seeks to address by describing several aspects of it, using examples and details, as well as quotes from relevant class readings (be sure to cite these correctly). C. Body of the Letter: What Your Organization Will Do Describe some points of actions your group will take and ways that you will spend donor funds to address aspects of the problem you have already described. Choose three to five specific courses of action. Do not make these two extensive. They should be manageable and practical. D. Your Summary and Conclusion: Asking for Money 1. Briefly restate the problem and your organization’s goals using new wording when possible. 2. Connect the funds you need to your organization’s goals 3. Make your request for money. 4. End with a final compelling statement of why the donor should give. III. Strategies and Guidelines 1. Use the writing process steps to help you through your letter. 2. Use the proofreading guide to help you edit and the Learning Center on campus for support. 5. Cite all quotes with the author and page number. Create a works cited page at the end of your essay for the works you discuss. (See the MLA guide and sample student essays in your textbook for examples and step-by-step help with MLA. You may also pick up a guide at the campus writing center and ask them for extra help.) 6. This is NOT a research essay. Most background information should come from common knowledge, your own prior knowledge and experience, and the readings from class/the text. However, you may choose to include up one additional research source if necessary, provided this is a reliable source that you can cite correctly. Please visit OWL at Purdue University for a complete MLA citation guide. You text also has a chapter on MLA citation. 7. Follow the correct essay format for font, spacing, margins, heading, etc. (SEE sample in this document.) IV. Formatting: You are required to format your essay in the way that follows to receive full credit. • Page number in upper right-hand corner (Use “Insert” and “Pg. #”) • Times New Roman 12 Pt. font • Heading in left corner with title, student name, essay 1 (or 2, etc.), Eng 2, and date • Heading is single spaced • Skip two lines to start typing body of text • Body of text is double spaced • Margins remain at 1 inch all around. • DO NOT skip lines between paragraphs • Indent each paragraph five lines • Use MLA format for citation Continue to the next page for format sample. Title of Your Campaign Project (Choose something compelling.) Student Name Essay 1 English 1 Date Dear _______, Start typing your essay here, two lines down from heading. The body of your essay is double spaced, but the heading is only single spaced. Note the page number in the upper right-hand corner. Note the exact content of the heading. There is no title page for short essays, nor is there a title across the top. For short essays of just a few pages, this format is standard. The title goes at the top of the heading. All words in the title are capitalized except pronouns, prepositions, and articles. Do not make your margins greater that one inch. Make sure you use Times New Roman 12 Point font. Do not include graphics or images of any kind in most essays for this class (see me if you think you have an exception). When you reach the end of your paragraph, just hit return and continue typing. Do not skip lines between your paragraphs or over-indent your paragraphs; indent only five lines as marked in the ruler. Do not attempt to write less for your essay by enlarging the font, margins, or spacing. This paragraph demonstrates a good length for an introduction. You next paragraph should start here. This is the way your essay should look. You may use this template to help you format your essay by saving it to your desktop and keeping the settings. You will, of course, have two to three pages when you finish, but this is what the first page would look like roughly. If you include a quote, be sure to cite the author and page number and to include a works cited page at the end of your essay.

English 1 Professor Nielsen Essay One Topic and Guidelines The Context You are a non-profit organization Director of Fundraising, and your goal is to convince a wealthy individual to make a substantial donation to your cause. Choose from one of the following projects derived from the social issues from the course readings below: 1. The Prison Project: Reducing the incarceration rate and numbers in the U.S. 2. Birth Control Advocacy and Access: Supporting a birth control education and free product distribution in the U.S and/or internationally. 3. LGBT Advocacy: Funding education, campaigning, and lobbying for LGBT rights in the U.S. 4. Equality in Education: Supporting funding and scholarships for schools and individuals from less advantaged populations. 5. Migrant Welfare and Protection: Creating safe housing, food, and education for refugees. 6. Something else related to social justice?????? (See me if you have your own project idea). (animal welfare, women’s advocacy, housing, student loans and tuition affordability, etc.) Make a case for a donation of $2 million dollars to your cause by writing a funding request letter to the potential donor. This request is essentially a persuasive essay designed to convince your reader to support your cause. Below is a suggested format for organizing your letter, as well as guidelines for your work. I. The Basics Due: Tuesday, September 29, at Start of Class (Rough Draft). And Tuesday, October 6, at Start of Class (Final Draft) Length: 3-4 Pgs., double spaced in the correct format (see sample paper format template at the end of this document for format.) Font: Times New Roman, 12PT. Margins: 1 inch all around. See sample format at the end of this document for further formatting information. You are required to submit using this format. Check the sample on page five of this document carefully. Editing: Be sure to use the proofreading guide. In particular, avoid the big five errors. Revising: Read over your draft carefully several times. We will work toward revision together in class, but you will also need to revise on your own. Visit the Learning center if you need extra support. II. Organization and Content (Sample Outline Follows.) Use an organized format for your essay. The best way to ensure strong organization is to map out a plan for the content of your essay, using an outline, clustering, or other graphic representation of your key ideas. One potential format follows. Sample Method of Organizing Your Funding Letter: A. The Opening Paragraph 1. Start with some brief striking details to provide the initial background to your letter: facts, figures, brief description of one aspect of the problem- something compelling. 2. End your paragraph with a statement that briefly announces/introduces your organization without yet going into detail about your mission. State that you are requesting a donation and that your letter will describe the need for this donation. (Your Thesis) B. Body of the Letter: The Problem Make a stronger case for the problem your organization seeks to address by describing several aspects of it, using examples and details, as well as quotes from relevant class readings (be sure to cite these correctly). C. Body of the Letter: What Your Organization Will Do Describe some points of actions your group will take and ways that you will spend donor funds to address aspects of the problem you have already described. Choose three to five specific courses of action. Do not make these two extensive. They should be manageable and practical. D. Your Summary and Conclusion: Asking for Money 1. Briefly restate the problem and your organization’s goals using new wording when possible. 2. Connect the funds you need to your organization’s goals 3. Make your request for money. 4. End with a final compelling statement of why the donor should give. III. Strategies and Guidelines 1. Use the writing process steps to help you through your letter. 2. Use the proofreading guide to help you edit and the Learning Center on campus for support. 5. Cite all quotes with the author and page number. Create a works cited page at the end of your essay for the works you discuss. (See the MLA guide and sample student essays in your textbook for examples and step-by-step help with MLA. You may also pick up a guide at the campus writing center and ask them for extra help.) 6. This is NOT a research essay. Most background information should come from common knowledge, your own prior knowledge and experience, and the readings from class/the text. However, you may choose to include up one additional research source if necessary, provided this is a reliable source that you can cite correctly. Please visit OWL at Purdue University for a complete MLA citation guide. You text also has a chapter on MLA citation. 7. Follow the correct essay format for font, spacing, margins, heading, etc. (SEE sample in this document.) IV. Formatting: You are required to format your essay in the way that follows to receive full credit. • Page number in upper right-hand corner (Use “Insert” and “Pg. #”) • Times New Roman 12 Pt. font • Heading in left corner with title, student name, essay 1 (or 2, etc.), Eng 2, and date • Heading is single spaced • Skip two lines to start typing body of text • Body of text is double spaced • Margins remain at 1 inch all around. • DO NOT skip lines between paragraphs • Indent each paragraph five lines • Use MLA format for citation Continue to the next page for format sample. Title of Your Campaign Project (Choose something compelling.) Student Name Essay 1 English 1 Date Dear _______, Start typing your essay here, two lines down from heading. The body of your essay is double spaced, but the heading is only single spaced. Note the page number in the upper right-hand corner. Note the exact content of the heading. There is no title page for short essays, nor is there a title across the top. For short essays of just a few pages, this format is standard. The title goes at the top of the heading. All words in the title are capitalized except pronouns, prepositions, and articles. Do not make your margins greater that one inch. Make sure you use Times New Roman 12 Point font. Do not include graphics or images of any kind in most essays for this class (see me if you think you have an exception). When you reach the end of your paragraph, just hit return and continue typing. Do not skip lines between your paragraphs or over-indent your paragraphs; indent only five lines as marked in the ruler. Do not attempt to write less for your essay by enlarging the font, margins, or spacing. This paragraph demonstrates a good length for an introduction. You next paragraph should start here. This is the way your essay should look. You may use this template to help you format your essay by saving it to your desktop and keeping the settings. You will, of course, have two to three pages when you finish, but this is what the first page would look like roughly. If you include a quote, be sure to cite the author and page number and to include a works cited page at the end of your essay.

Assignment 10 Due: 11:59pm on Wednesday, April 23, 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: Ka Kc Correct 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: I2 I1 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: Correct 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: Correct I2/I1 = 32 rpm s  = 440 rad s2 s  = 12 rev Constant Angular Acceleration in the Kitchen 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. Hint 1. How to approach the problem Recall from your study of kinematics the three equations of motion derived for systems undergoing constant linear acceleration. You are now studying systems undergoing constant angular acceleration and will need to work with the three analogous equations of motion. Collect your known quantities and then determine which of the angular kinematic equations is appropriate to find the angular acceleration . Hint 2. Find the angular velocity of the salad spinner while Dario is spinning it What is the angular velocity of the salad spinner as Dario is spinning it? Express your answer numerically in degrees per second. Hint 1. Converting rotations to degrees When the salad spinner spins through one revolution, it turns through 360 degrees. ANSWER: Hint 3. Find the angular distance the salad spinner travels as it comes to rest Through how many degrees does the salad spinner rotate as it comes to rest? Express your answer numerically in degrees. Hint 1. Converting rotations to degrees  0 = 1440 degrees/s  =  − 0 One revolution is equivalent to 360 degrees. ANSWER: Hint 4. Determine which equation to use You know the initial and final velocities of the system and the angular distance through which the spinner rotates as it comes to a stop. Which equation should be used to solve for the unknown constant angular acceleration ? ANSWER: ANSWER: Correct Part B How long does it take for the salad spinner to come to rest? Express your answer numerically in seconds.  = 2160 degrees   = 0 + 0t+  1 2 t2  = 0 + t = + 2( − ) 2 20 0  = -480 degrees/s2 Hint 1. How to approach the problem Again, you will need the equations of rotational kinematics that apply to situations of constant angular acceleration. Collect your known quantities and then determine which of the angular kinematic equations is appropriate to find . Hint 2. Determine which equation to use You have the initial and final velocities of the system and the angular acceleration, which you found in the previous part. Which is the best equation to use to solve for the unknown time ? ANSWER: ANSWER: Correct ± 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. Hint 1. Average acceleration Recall that if the angular velocity decreases uniformly, the angular acceleration will remain constant. Therefore, the angular acceleration is just the total change in angular velocity divided by t t  = 0 + 0t+  1 2 t2  = 0 + t = + 2( − ) 2 20 0 t = 3.00 s rev/min rev/min s  the total change in time. Be careful of the sign of the angular acceleration. ANSWER: Correct Part B Find the number of revolutions made by the fan blades during the time that they are slowing down in Part A. Hint 1. Determine the correct kinematic equation Which of the following kinematic equations is best suited to this problem? Here and are the initial and final angular velocities, is the elapsed time, is the constant angular acceleration, and and are the initial and final angular displacements. Hint 1. How to chose the right equation Notice that you were given in the problem introduction the initial and final speeds, as well as the length of time between them. In this problem, you are asked to find the number of revolutions (which here is the change in angular displacement, ). If you already found the angular acceleration in Part A, you could use that as well, but you would end up using a more complex equation. Also, in general, it is somewhat favorable to use given quantities instead of quantities that you have calculated. ANSWER:  = -1.10 rev/s2 0  t  0   − 0  = 0 + t  = 0 + t+  1 2 t2 = + 2( − ) 2 20 0 − 0 = (+ )t 1 2 0 ANSWER: Correct 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? Hint 1. Finding the total time for spin down To find the total time for spin down, just calculate when the velocity will equal zero. This is accomplished by setting the initial velocity plus the acceleration multipled by the time equal to zero and then solving for the time. One can then just subtract the time it took to reach 250 from the total time. Be careful of your signs when you set up the equation. ANSWER: Correct 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: 29.0 rev rev/min 3.79 s g g cm rpm g Correct 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? Express your answer with the appropriate units. ANSWER: Correct 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: v = 3.2 ms g cm J 3.65 ms cm g rpm K = 4.4 J Correct 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. Hint 1. Conditions for equilibrium If the blocks had the same mass, the system would be in equilibrium. The blocks would have zero acceleration and the tension in each part of the cord would equal the weight of each block. Both parts of the cord would then pull with equal force on the pulley, resulting in a zero net torque and no rotation of the pulley. Is this still the case in the current situation where block B has twice the mass of block A? Hint 2. Rotational analogue of Newton’s second law The net torque of all the forces acting on a rigid body is proportional to the angular acceleration of the body net  and is given by , where is the moment of inertia of the body. Hint 3. Relation between linear and angular acceleration A particle that rotates with angular acceleration has linear acceleration equal to , where is the distance of the particle from the axis of rotation. In the present case, where there is no slipping or stretching of the cord, the cord and the pulley must move together at the same speed. Therefore, if the cord moves with linear acceleration , the pulley must rotate with angular acceleration , where is the radius of the pulley. ANSWER: Correct Part B What happens when block B moves downward? Hint 1. How to approach the problem To determine whether the tensions in both parts of the cord are equal, it is convenient to write a mathematical expression for the net torque on the pulley. This will allow you to relate the tensions in the cord to the pulley’s angular acceleration. Hint 2. Find the net torque on the pulley Let’s assume that the tensions in both parts of the cord are different. Let be the tension in the right cord and the tension in the left cord. If is the radius of the pulley, what is the net torque acting on the pulley? Take the positive sense of rotation to be counterclockwise. Express your answer in terms of , , and . net = I I  a a = R R a  = a R R The acceleration of the blocks is zero. The net torque on the pulley is zero. The angular acceleration of the pulley is nonzero. T1 T2 R net T1 T2 R Hint 1. Torque The torque of a force with respect to a point is defined as the product of the magnitude times the perpendicular distance between the line of action of and the point . In other words, . ANSWER: ANSWER: Correct Note that if the pulley were stationary (as in many systems where only linear motion is studied), then the tensions in both parts of the cord would be equal. However, if the pulley rotates with a certain angular acceleration, as in the present situation, the tensions must be different. If they were equal, the pulley could not have an angular acceleration. 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.  F  O F l F  O  = Fl net = R(T2 − T1 ) The left cord pulls on the pulley with greater force than the right cord. The left and right cord pull with equal force on the pulley. The right cord pulls on the pulley with greater force than the left cord. ANSWER: Correct Part B What is the direction of net torque about the axle? ANSWER: Correct 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.  = 0.20 Nm Clockwise Counterclockwise kg cm kg ANSWER: Correct 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: Correct 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. Hint 1. Find the distance from the axis to the center of mass Find the distance appropriate to this problem. That is, find the perpendicular distance from the center of mass of the rod to the axis passing through one end of the rod.  = 41 Nm 45  = 29 Nm Icm Ip Ip = Icm + Md2 d M L m Icm = m 1 12 L2 Iend Iend m L d ANSWER: ANSWER: Correct 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. Hint 1. Find the distance from the axis to the axis Find the perpendicular distance from the center of mass axis to the new edge axis (axis labeled p in the figure). ANSWER: d = L 2 Iend = mL2 3 m a Icm Icm = m 1 6 a2 Iedge Iedge m a o p d ANSWER: Correct 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. ANSWER: Correct Part B How many revolutions does it make before reaching full speed? Express your answer using two significant figures. ANSWER: d = a 2 Iedge = 2ma2 3 cm s rpm 2.5 × 10−5 kg m2 = 1.8×10−3  Nm Correct 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: Correct 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. N = 48 rev kgm2 rad/s2 8.14 N  m kg kg m 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: Correct 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 kg d = 1.4 m M1 = 3.6 kg L = 0.66 m L1 = 0.33 m L2 = 0.15 m  = 17 g = 9.8 m/s2 Find the tension in the deltoid muscle. Express the tension in newtons, to the nearest integer. Hint 1. Nature of the problem Remember that this is a statics problem, so all forces and torques are balanced (their sums equal zero). Hint 2. Origin of torque Calculate the torque about the point at which the arm attaches to the rest of the body. This allows one to balance the torques without having to worry about the undefined forces at this point. Hint 3. Adding up the torques Add up the torques about the point in which the humerus attaches to the body. Answer in terms of , , , , , and . Remember that counterclockwise torque is positive. ANSWER: ANSWER: Correct 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. T L1 L2 M1 g T  total = 0 = L1M1g − Tsin()L2 T = 265 N Fy Hint 1. Total forces involved Recall that there are three vertical forces in this problem: the force of gravity acting on the bone, the force from the vertical component of the muscle tension, and the force exerted by the scapula on the humerus (where it attaches to the rest of the body). ANSWER: Correct 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: Correct ± 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). |Fy| = 42 N Fx |Fx| = 254 N F 1 F  2 F  3 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. Hint 1. Finding torque about pivot from What is the magnitude of the torque | | provided by around the pivot point? Give your answer numerically in newton-meters to two significant figures. ANSWER: ANSWER: Correct 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. F3 = 0 F1 = 12 N F 2 F 1   1 F  1 |  1 | = 0.36 N  m F2 = 4.5 N I = 9 kg m2 F1 = 12 N F2 = 27 N F3 = 0 t 45  Hint 1. Find the net torque about the pivot What is the magnitude of the total torque around the pivot point? Answer numerically in newton-meters to two significant figures. ANSWER: Hint 2. Calculate Given the total torque around the pivot point, what is , the magnitude of the angular acceleration? Express your answer numerically in radians per second squared to two significant figures. Hint 1. Equation for If you know the magnitude of the total torque ( ) and the rotational inertia ( ), you can then find the rotational acceleration ( ) from ANSWER: Hint 3. Description of angular kinematics Now that you know the angular acceleration, this is a problem in rotational kinematics; find the time needed to go through a given angle . For constant acceleration ( ) and starting with (where is angular speed) the relation is given by which is analogous to the expression for linear displacement ( ) with constant acceleration ( ) starting from rest, | p ivot| | p ivot| = 1.8 N  m    vot Ivot  pivot = Ipivot.  = 0.20 radians/s2    = 0   = 1  , 2 t2 x a . ANSWER: Correct 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. Hint 1. Find the required component of Only the tangential (perpendicular) component of (call it ) provides a torque. What is ? Answer in terms of . You will need to evaluate any trigonometric functions. ANSWER: ANSWER: Correct x = 1 a 2 t2 t = 2.8 s F1 = 12 N F2 = 0 F3 F3 F 3 F  3 F3t F3t F3 F3t = 1 2 F3 F3 = 9.0 N 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: Correct 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: Correct 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: cm m/s 833 rpm 48.0 ms 0 ms Correct 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. ANSWER: Correct Problem 12.45 Part A What is the magnitude of the angular momentum of the 780 rotating bar in the figure ? g m/s 0.583 J g ANSWER: Correct Part B What is the direction of the angular momentum of the bar ? ANSWER: Correct Problem 12.46 Part A What is the magnitude of the angular momentum of the 2.20 , 4.60-cm-diameter rotating disk in the figure ? 3.27 kgm2/s into the page out of the page kg ANSWER: Correct Part B What is its direction? ANSWER: Correct 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. 3.66×10−2 kgm /s 2 x direction -x direction y direction -y direction z direction -z direction m 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: Correct 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.  = 47 m kg kg m 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: Correct 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: Correct 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: F1 = 670 N F2 = 900 N kg m kg 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. Hint 1. How to approach the problem Draw a picture of the four forces acting on the beam, indicating both their direction and the place on the beam that the forces are acting. Choose a coordinate system with a direction for the axis along the beam, and indicate the position of the boy. What is the net force on the beam if it is stationary? Just before the beam tips, the force of the left support on the beam is zero. Using the zero net force condition, what is the force due to the right support just before the beam tips? For the beam to remain stationary, what must be zero besides the net force on the beam? Choose a point on the beam, and compute the net torque on the beam about that point. Be sure to choose a positive direction for the rotation axis and therefore the torques. Using the zero torque condition, what is the position of the boy on the beam just prior to tipping? How far is this position from the right edge of the beam? ANSWER: Correct d = 2.0 m 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: Correct Part B How much energy is stored in the flywheel? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct 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: m kg rpm N  m t = 250 s = 1.1×106 E J s Correct 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: Correct 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 ? P = 2.4×105 W  = 1800 Nm kg rpm s Express your answer with the appropriate units. ANSWER: Correct 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. 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: 5.76 N kg cm  = 22 rad s2 Correct 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: Correct 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: Incorrect; Try Again Score Summary:  = 6.6 rad s kg rev/s kg cm cm kg cm kg cm cm 2 = Your score on this assignment is 95.7%. You received 189.42 out of a possible total of 198 points.

Assignment 10 Due: 11:59pm on Wednesday, April 23, 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: Ka Kc Correct 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: I2 I1 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: Correct 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: Correct I2/I1 = 32 rpm s  = 440 rad s2 s  = 12 rev Constant Angular Acceleration in the Kitchen 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. Hint 1. How to approach the problem Recall from your study of kinematics the three equations of motion derived for systems undergoing constant linear acceleration. You are now studying systems undergoing constant angular acceleration and will need to work with the three analogous equations of motion. Collect your known quantities and then determine which of the angular kinematic equations is appropriate to find the angular acceleration . Hint 2. Find the angular velocity of the salad spinner while Dario is spinning it What is the angular velocity of the salad spinner as Dario is spinning it? Express your answer numerically in degrees per second. Hint 1. Converting rotations to degrees When the salad spinner spins through one revolution, it turns through 360 degrees. ANSWER: Hint 3. Find the angular distance the salad spinner travels as it comes to rest Through how many degrees does the salad spinner rotate as it comes to rest? Express your answer numerically in degrees. Hint 1. Converting rotations to degrees  0 = 1440 degrees/s  =  − 0 One revolution is equivalent to 360 degrees. ANSWER: Hint 4. Determine which equation to use You know the initial and final velocities of the system and the angular distance through which the spinner rotates as it comes to a stop. Which equation should be used to solve for the unknown constant angular acceleration ? ANSWER: ANSWER: Correct Part B How long does it take for the salad spinner to come to rest? Express your answer numerically in seconds.  = 2160 degrees   = 0 + 0t+  1 2 t2  = 0 + t = + 2( − ) 2 20 0  = -480 degrees/s2 Hint 1. How to approach the problem Again, you will need the equations of rotational kinematics that apply to situations of constant angular acceleration. Collect your known quantities and then determine which of the angular kinematic equations is appropriate to find . Hint 2. Determine which equation to use You have the initial and final velocities of the system and the angular acceleration, which you found in the previous part. Which is the best equation to use to solve for the unknown time ? ANSWER: ANSWER: Correct ± 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. Hint 1. Average acceleration Recall that if the angular velocity decreases uniformly, the angular acceleration will remain constant. Therefore, the angular acceleration is just the total change in angular velocity divided by t t  = 0 + 0t+  1 2 t2  = 0 + t = + 2( − ) 2 20 0 t = 3.00 s rev/min rev/min s  the total change in time. Be careful of the sign of the angular acceleration. ANSWER: Correct Part B Find the number of revolutions made by the fan blades during the time that they are slowing down in Part A. Hint 1. Determine the correct kinematic equation Which of the following kinematic equations is best suited to this problem? Here and are the initial and final angular velocities, is the elapsed time, is the constant angular acceleration, and and are the initial and final angular displacements. Hint 1. How to chose the right equation Notice that you were given in the problem introduction the initial and final speeds, as well as the length of time between them. In this problem, you are asked to find the number of revolutions (which here is the change in angular displacement, ). If you already found the angular acceleration in Part A, you could use that as well, but you would end up using a more complex equation. Also, in general, it is somewhat favorable to use given quantities instead of quantities that you have calculated. ANSWER:  = -1.10 rev/s2 0  t  0   − 0  = 0 + t  = 0 + t+  1 2 t2 = + 2( − ) 2 20 0 − 0 = (+ )t 1 2 0 ANSWER: Correct 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? Hint 1. Finding the total time for spin down To find the total time for spin down, just calculate when the velocity will equal zero. This is accomplished by setting the initial velocity plus the acceleration multipled by the time equal to zero and then solving for the time. One can then just subtract the time it took to reach 250 from the total time. Be careful of your signs when you set up the equation. ANSWER: Correct 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: 29.0 rev rev/min 3.79 s g g cm rpm g Correct 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? Express your answer with the appropriate units. ANSWER: Correct 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: v = 3.2 ms g cm J 3.65 ms cm g rpm K = 4.4 J Correct 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. Hint 1. Conditions for equilibrium If the blocks had the same mass, the system would be in equilibrium. The blocks would have zero acceleration and the tension in each part of the cord would equal the weight of each block. Both parts of the cord would then pull with equal force on the pulley, resulting in a zero net torque and no rotation of the pulley. Is this still the case in the current situation where block B has twice the mass of block A? Hint 2. Rotational analogue of Newton’s second law The net torque of all the forces acting on a rigid body is proportional to the angular acceleration of the body net  and is given by , where is the moment of inertia of the body. Hint 3. Relation between linear and angular acceleration A particle that rotates with angular acceleration has linear acceleration equal to , where is the distance of the particle from the axis of rotation. In the present case, where there is no slipping or stretching of the cord, the cord and the pulley must move together at the same speed. Therefore, if the cord moves with linear acceleration , the pulley must rotate with angular acceleration , where is the radius of the pulley. ANSWER: Correct Part B What happens when block B moves downward? Hint 1. How to approach the problem To determine whether the tensions in both parts of the cord are equal, it is convenient to write a mathematical expression for the net torque on the pulley. This will allow you to relate the tensions in the cord to the pulley’s angular acceleration. Hint 2. Find the net torque on the pulley Let’s assume that the tensions in both parts of the cord are different. Let be the tension in the right cord and the tension in the left cord. If is the radius of the pulley, what is the net torque acting on the pulley? Take the positive sense of rotation to be counterclockwise. Express your answer in terms of , , and . net = I I  a a = R R a  = a R R The acceleration of the blocks is zero. The net torque on the pulley is zero. The angular acceleration of the pulley is nonzero. T1 T2 R net T1 T2 R Hint 1. Torque The torque of a force with respect to a point is defined as the product of the magnitude times the perpendicular distance between the line of action of and the point . In other words, . ANSWER: ANSWER: Correct Note that if the pulley were stationary (as in many systems where only linear motion is studied), then the tensions in both parts of the cord would be equal. However, if the pulley rotates with a certain angular acceleration, as in the present situation, the tensions must be different. If they were equal, the pulley could not have an angular acceleration. 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.  F  O F l F  O  = Fl net = R(T2 − T1 ) The left cord pulls on the pulley with greater force than the right cord. The left and right cord pull with equal force on the pulley. The right cord pulls on the pulley with greater force than the left cord. ANSWER: Correct Part B What is the direction of net torque about the axle? ANSWER: Correct 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.  = 0.20 Nm Clockwise Counterclockwise kg cm kg ANSWER: Correct 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: Correct 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. Hint 1. Find the distance from the axis to the center of mass Find the distance appropriate to this problem. That is, find the perpendicular distance from the center of mass of the rod to the axis passing through one end of the rod.  = 41 Nm 45  = 29 Nm Icm Ip Ip = Icm + Md2 d M L m Icm = m 1 12 L2 Iend Iend m L d ANSWER: ANSWER: Correct 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. Hint 1. Find the distance from the axis to the axis Find the perpendicular distance from the center of mass axis to the new edge axis (axis labeled p in the figure). ANSWER: d = L 2 Iend = mL2 3 m a Icm Icm = m 1 6 a2 Iedge Iedge m a o p d ANSWER: Correct 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. ANSWER: Correct Part B How many revolutions does it make before reaching full speed? Express your answer using two significant figures. ANSWER: d = a 2 Iedge = 2ma2 3 cm s rpm 2.5 × 10−5 kg m2 = 1.8×10−3  Nm Correct 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: Correct 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. N = 48 rev kgm2 rad/s2 8.14 N  m kg kg m 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: Correct 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 kg d = 1.4 m M1 = 3.6 kg L = 0.66 m L1 = 0.33 m L2 = 0.15 m  = 17 g = 9.8 m/s2 Find the tension in the deltoid muscle. Express the tension in newtons, to the nearest integer. Hint 1. Nature of the problem Remember that this is a statics problem, so all forces and torques are balanced (their sums equal zero). Hint 2. Origin of torque Calculate the torque about the point at which the arm attaches to the rest of the body. This allows one to balance the torques without having to worry about the undefined forces at this point. Hint 3. Adding up the torques Add up the torques about the point in which the humerus attaches to the body. Answer in terms of , , , , , and . Remember that counterclockwise torque is positive. ANSWER: ANSWER: Correct 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. T L1 L2 M1 g T  total = 0 = L1M1g − Tsin()L2 T = 265 N Fy Hint 1. Total forces involved Recall that there are three vertical forces in this problem: the force of gravity acting on the bone, the force from the vertical component of the muscle tension, and the force exerted by the scapula on the humerus (where it attaches to the rest of the body). ANSWER: Correct 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: Correct ± 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). |Fy| = 42 N Fx |Fx| = 254 N F 1 F  2 F  3 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. Hint 1. Finding torque about pivot from What is the magnitude of the torque | | provided by around the pivot point? Give your answer numerically in newton-meters to two significant figures. ANSWER: ANSWER: Correct 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. F3 = 0 F1 = 12 N F 2 F 1   1 F  1 |  1 | = 0.36 N  m F2 = 4.5 N I = 9 kg m2 F1 = 12 N F2 = 27 N F3 = 0 t 45  Hint 1. Find the net torque about the pivot What is the magnitude of the total torque around the pivot point? Answer numerically in newton-meters to two significant figures. ANSWER: Hint 2. Calculate Given the total torque around the pivot point, what is , the magnitude of the angular acceleration? Express your answer numerically in radians per second squared to two significant figures. Hint 1. Equation for If you know the magnitude of the total torque ( ) and the rotational inertia ( ), you can then find the rotational acceleration ( ) from ANSWER: Hint 3. Description of angular kinematics Now that you know the angular acceleration, this is a problem in rotational kinematics; find the time needed to go through a given angle . For constant acceleration ( ) and starting with (where is angular speed) the relation is given by which is analogous to the expression for linear displacement ( ) with constant acceleration ( ) starting from rest, | p ivot| | p ivot| = 1.8 N  m    vot Ivot  pivot = Ipivot.  = 0.20 radians/s2    = 0   = 1  , 2 t2 x a . ANSWER: Correct 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. Hint 1. Find the required component of Only the tangential (perpendicular) component of (call it ) provides a torque. What is ? Answer in terms of . You will need to evaluate any trigonometric functions. ANSWER: ANSWER: Correct x = 1 a 2 t2 t = 2.8 s F1 = 12 N F2 = 0 F3 F3 F 3 F  3 F3t F3t F3 F3t = 1 2 F3 F3 = 9.0 N 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: Correct 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: Correct 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: cm m/s 833 rpm 48.0 ms 0 ms Correct 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. ANSWER: Correct Problem 12.45 Part A What is the magnitude of the angular momentum of the 780 rotating bar in the figure ? g m/s 0.583 J g ANSWER: Correct Part B What is the direction of the angular momentum of the bar ? ANSWER: Correct Problem 12.46 Part A What is the magnitude of the angular momentum of the 2.20 , 4.60-cm-diameter rotating disk in the figure ? 3.27 kgm2/s into the page out of the page kg ANSWER: Correct Part B What is its direction? ANSWER: Correct 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. 3.66×10−2 kgm /s 2 x direction -x direction y direction -y direction z direction -z direction m 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: Correct 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.  = 47 m kg kg m 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: Correct 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: Correct 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: F1 = 670 N F2 = 900 N kg m kg 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. Hint 1. How to approach the problem Draw a picture of the four forces acting on the beam, indicating both their direction and the place on the beam that the forces are acting. Choose a coordinate system with a direction for the axis along the beam, and indicate the position of the boy. What is the net force on the beam if it is stationary? Just before the beam tips, the force of the left support on the beam is zero. Using the zero net force condition, what is the force due to the right support just before the beam tips? For the beam to remain stationary, what must be zero besides the net force on the beam? Choose a point on the beam, and compute the net torque on the beam about that point. Be sure to choose a positive direction for the rotation axis and therefore the torques. Using the zero torque condition, what is the position of the boy on the beam just prior to tipping? How far is this position from the right edge of the beam? ANSWER: Correct d = 2.0 m 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: Correct Part B How much energy is stored in the flywheel? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct 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: m kg rpm N  m t = 250 s = 1.1×106 E J s Correct 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: Correct 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 ? P = 2.4×105 W  = 1800 Nm kg rpm s Express your answer with the appropriate units. ANSWER: Correct 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. 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: 5.76 N kg cm  = 22 rad s2 Correct 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: Correct 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: Incorrect; Try Again Score Summary:  = 6.6 rad s kg rev/s kg cm cm kg cm kg cm cm 2 = Your score on this assignment is 95.7%. You received 189.42 out of a possible total of 198 points.

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AUCS 340: Ethics in the Professions Individual Written Assignment #1 Medical Ethics: Historical names, dates and ethical theories assignment As you read chapters 1 and 2 in the “Ethics and Basic Law for Medical Imaging Professionals” textbook you will be responsible for identifying and explaining each of the following items from the list below. You will respond in paragraph format with correct spelling and grammar expected for each paragraph. Feel free to have more than one paragraph for each item, although in most instances a single paragraph response is sufficient. If you reference material in addition to what is available in the textbook it must be appropriately cited in your work using either APA or MLA including a references cited page. The use of Wikipedia.com is not a recognized peer reviewed source so please do not use that as a reference. When responding about individuals it is necessary to indicate a year or time period that the person discussed/developed their particular ethical theory so that you can look at and appreciate the historical background to the development of ethical theories and decision making. Respond to the following sixteen items. (They are in random order from your reading) 1. Francis Bacon 2. Isaac Newton 3. Prima Facie Duties – Why do they exist? LIST AND DEFINE ALL TERMS 4. Hippocrates 5. W.D. Ross – what do the initials stand for in his name and what was his contribution to the study of ethics? 6. Microallocation – define the term and provide an example separate from the book example (You should develop your own example rather than looking for an online example; this will use your critical thinking skills. Consider an application to your own profession as microallocation is NOT limited to the medical field.) 7. Deontology – Discuss at length the basic types/concepts of this theory 8. Thomas Aquinas – 1) Discuss the ethical theory developed by Aquinas, 2) his religious affiliation, 3) why that was so important to his ethical premise and 4) discuss the type of ethical issues resolved to this day using this theory. 9. Macroallocation – define and provide an example separate from the book example (You should develop your own example rather than looking for an online example; this will use your critical thinking skills. Consider an application to your own profession as macroallocation is NOT limited to the medical field.) 10. David Hume 11. Rodericus Castro 12. Plato and “The Republic” 13. Pythagoras 14. Teleology – Discuss at length the basic types/concepts of this theory 15. Core Values – Why do they exist? LIST AND DEFINE ALL TERMS 16. Develop a timeline that reflects the ethical theories as developed by the INDIVIDUALS presented in this assignment. This assignment is due Saturday March 14th at NOON and is graded as a homework assignment. Grading: Paragraph Formation = 20% of grade (bulleted lists are acceptable for some answers) Answers inclusive of major material for answer = 40% of grade Creation of Timeline = 10% of grade Sentence structure, application of correct spelling and grammar = 20% of grade References (if utilized) = 10% of grade; references should be submitted on a separate references cited page. Otherwise this 10% of the assignment grade will be considered under the sentence structure component for 30% of the grade. It is expected that the finished assignment will be two – three pages of text, double spaced, using 12 font and standard page margins.

AUCS 340: Ethics in the Professions Individual Written Assignment #1 Medical Ethics: Historical names, dates and ethical theories assignment As you read chapters 1 and 2 in the “Ethics and Basic Law for Medical Imaging Professionals” textbook you will be responsible for identifying and explaining each of the following items from the list below. You will respond in paragraph format with correct spelling and grammar expected for each paragraph. Feel free to have more than one paragraph for each item, although in most instances a single paragraph response is sufficient. If you reference material in addition to what is available in the textbook it must be appropriately cited in your work using either APA or MLA including a references cited page. The use of Wikipedia.com is not a recognized peer reviewed source so please do not use that as a reference. When responding about individuals it is necessary to indicate a year or time period that the person discussed/developed their particular ethical theory so that you can look at and appreciate the historical background to the development of ethical theories and decision making. Respond to the following sixteen items. (They are in random order from your reading) 1. Francis Bacon 2. Isaac Newton 3. Prima Facie Duties – Why do they exist? LIST AND DEFINE ALL TERMS 4. Hippocrates 5. W.D. Ross – what do the initials stand for in his name and what was his contribution to the study of ethics? 6. Microallocation – define the term and provide an example separate from the book example (You should develop your own example rather than looking for an online example; this will use your critical thinking skills. Consider an application to your own profession as microallocation is NOT limited to the medical field.) 7. Deontology – Discuss at length the basic types/concepts of this theory 8. Thomas Aquinas – 1) Discuss the ethical theory developed by Aquinas, 2) his religious affiliation, 3) why that was so important to his ethical premise and 4) discuss the type of ethical issues resolved to this day using this theory. 9. Macroallocation – define and provide an example separate from the book example (You should develop your own example rather than looking for an online example; this will use your critical thinking skills. Consider an application to your own profession as macroallocation is NOT limited to the medical field.) 10. David Hume 11. Rodericus Castro 12. Plato and “The Republic” 13. Pythagoras 14. Teleology – Discuss at length the basic types/concepts of this theory 15. Core Values – Why do they exist? LIST AND DEFINE ALL TERMS 16. Develop a timeline that reflects the ethical theories as developed by the INDIVIDUALS presented in this assignment. This assignment is due Saturday March 14th at NOON and is graded as a homework assignment. Grading: Paragraph Formation = 20% of grade (bulleted lists are acceptable for some answers) Answers inclusive of major material for answer = 40% of grade Creation of Timeline = 10% of grade Sentence structure, application of correct spelling and grammar = 20% of grade References (if utilized) = 10% of grade; references should be submitted on a separate references cited page. Otherwise this 10% of the assignment grade will be considered under the sentence structure component for 30% of the grade. It is expected that the finished assignment will be two – three pages of text, double spaced, using 12 font and standard page margins.

Francis Bacon was a 16th century ethical theorist who was … Read More...
The 1998 Rome Charter was drafted and negotiated and at critical time in the history of international politics. In addition to numerous crimes by states, organizations, and individuals; the national political interests and sovereignty of powerful nation-states was challenged. What role did UN politics play in drafting and the Charter? According to Cassese, what crimes fall within the jurisdiction of the ICC and under what conditions can the court take action? Use the terms, Articles, and Conventions below to discuss this question. The U.N. Charter The Assembly of States The ILC The Preparatory Commission The Security Council The Vienna Conventions UN Security Council Resolution 1593 Article 18 SOFA Agreements Rome Statute Articles 1-5 Propio Motu Mens Rea Nullum Crimen Sine Lege The Nuremberg Trials

The 1998 Rome Charter was drafted and negotiated and at critical time in the history of international politics. In addition to numerous crimes by states, organizations, and individuals; the national political interests and sovereignty of powerful nation-states was challenged. What role did UN politics play in drafting and the Charter? According to Cassese, what crimes fall within the jurisdiction of the ICC and under what conditions can the court take action? Use the terms, Articles, and Conventions below to discuss this question. The U.N. Charter The Assembly of States The ILC The Preparatory Commission The Security Council The Vienna Conventions UN Security Council Resolution 1593 Article 18 SOFA Agreements Rome Statute Articles 1-5 Propio Motu Mens Rea Nullum Crimen Sine Lege The Nuremberg Trials

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