Faraday’s Law of Induction 1a. Problem 28.9 b. Problem 28.39 2. Problem 28.43 3. Problem 28.71 Inductance 4a. Problem 28.56 b. Estimate the magnetic energy stored in the first kilometer of atmosphere above Milwaukee. Compare your answer to the energy stored in a 15-gallon gas tank. ugasoline=120 M J/gal 5. Problem 28.65 Feel free to sketch by hand, rather than using a “spreadsheet program.” 6a. Problem 29.83 (From the next chapter!) b. If the power delivered to the residents is 20kW, how much current flows on either side of the transformer? c. The 2000-volt distribution lines have a total resistance of 3Ω, how much power is lost as thermal dissipation? How much would be lost if those same lines operated at 240V? Hint: Use your answers from part b to calculate the powers in part c… EC1: Problem 28.53 EC2: Problem 28.80

Faraday’s Law of Induction 1a. Problem 28.9 b. Problem 28.39 2. Problem 28.43 3. Problem 28.71 Inductance 4a. Problem 28.56 b. Estimate the magnetic energy stored in the first kilometer of atmosphere above Milwaukee. Compare your answer to the energy stored in a 15-gallon gas tank. ugasoline=120 M J/gal 5. Problem 28.65 Feel free to sketch by hand, rather than using a “spreadsheet program.” 6a. Problem 29.83 (From the next chapter!) b. If the power delivered to the residents is 20kW, how much current flows on either side of the transformer? c. The 2000-volt distribution lines have a total resistance of 3Ω, how much power is lost as thermal dissipation? How much would be lost if those same lines operated at 240V? Hint: Use your answers from part b to calculate the powers in part c… EC1: Problem 28.53 EC2: Problem 28.80

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Chapter 03 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Components and Structure of the Atom Learning Goal: To specify the basic components of the atom and describe our modern conception of its structure. Part A The atom consists of three types of subatomic particles: protons, neutrons, and electrons. The electron is by far the lightest of the three, while the much heavier proton and neutron have masses very similar to each other. Two of the types of particles carry an electrical charge, while the third is neutral. Label the subatomic particles and appropriate charges by their relative locations. Identify the subatomic particles by dragging the appropriate labels to their respective targets. Hint 1. Which subatomic particles carry electric charge? Of the three subatomic particles, two carry equal but opposite charges. Select the two correct statements that match the subatomic particle with the appropriate charge. Check all that apply. ANSWER: Hint 2. Which subatomic particles are not found in the nucleus? Protons and electrons carry equal but opposite charges. Atomic nuclei are positively charged and are not composed of negatively charged particles. Which types of subatomic particles cannot be located within the nucleus? Select any that apply. ANSWER: ANSWER: The electron carries a positive charge. The proton carries a positive charge. The neutron carries a positive charge. The proton carries a negative charge. The electron carries a negative charge. The neutron carries a negative charge. neutrons electrons protons Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 14 5/21/2014 8:02 PM Correct This image represents the classical model of the atom proposed by Niels Bohr. Although this model has changed slightly as the result of modern scientific discoveries, it does help in understanding the relative locations of the subatomic particles in the atom. Notice that the protons and neutrons are bound in the nucleus, while the electrons are located in the space surrounding the nucleus. Part B Of the three types of subatomic particles, only neutrons do not carry charge. Protons carry a positive charge, and electrons carry a negative charge. Protons and neutrons are bound in the nucleus, while electrons orbit the nucleus. When the number of each type of subatomic particle in an atom changes, the characteristics defining the atom also change. Match the appropriate phrases with the type of subatomic particle that completes the defining characteristic. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. Hint 1. What type of subatomic particle is lost or gained when an ion forms? For any atom of a given element to go from being neutral ( ) to being ionized ( ), what type of subatomic particle must be lost or gained? Select all that apply. ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 14 5/21/2014 8:02 PM Hint 2. What type of subatomic particle identifies an element? When identifying the element classification of a particular atom, which type of subatomic particle is used? ANSWER: ANSWER: Correct The number of each type of subatomic particle plays an important role in the characteristics of the atom. The general element classification (hydrogen, carbon, oxygen, etc.) is governed by the number of protons in the nucleus. If the number of protons changes in an atom, so does the type of element. The electrons are the only type of subatomic particle not in the nucleus. They orbit around the nucleus, bound by the electromagnetic force. When electrons are lost or gained by a neutral atom, the charge balance shifts, resulting in the atom becoming an ion. Ions can be either positive when electrons are lost or negative when electrons are gained. Part C In the classical view of the atom, Bohr pictured electrons orbiting the positively charged nucleus similar to how the planets orbit the Sun. While this picture was not entirely correct, it provides a good framework in which to make calculations about the energies of electrons. Different from the predictions of Newtonian mechanics, which allows any energy to be possible, Bohr described the electron orbits (now called orbitals) as having specific energies. Rank the following electron energy states according to their electron energies. Rank from highest to lowest energies. Hint 1. What are the definitions of orbital, ground state, and excited state? Define orbital, ground state, and excited state. loss of an electron loss of a proton loss of a neutron gain of an electron gain of a proton gain of a neutron electron proton neutron Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 14 5/21/2014 8:02 PM Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. ANSWER: Hint 2. How does the state change when an electron absorbs energy? Electrons can absorb energy either from light radiation or from collisions with other atoms. If an electron is in the first excited energy state and absorbs enough energy to go to the next higher energy state, into what state will the electron transition? ANSWER: ANSWER: the ground state the second excited state the third excited state Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 14 5/21/2014 8:02 PM Correct Excited states refer to the energy of an electron. The higher the state, the higher the energy of the electron. The electron energies of each orbital are fixed. The energy required for an electron to transition between each orbital is an exact value, corresponding to the difference between the orbital energies. Any energy more or less than these precise differences cannot be used by the electron to make a transition; only the energies equal to the full values can induce a transition. Part D The Bohr model accounted for most of the general characteristics of the atom. However, the modern model based on quantum mechanics explains that, although the energy of each orbital is fixed, the orbital radius is actually an average distance. The result is a “cloud” where the electron is most likely to be located. The following is an image of an atom of hydrogen, consisting of one proton, zero neutrons, and one electron. When an electron is excited to different energy levels, the radius from the nucleus also changes. Rank the following electron energy states according to the average distance of the electron from the nucleus. Rank from largest to smallest distances. Hint 1. What is the relationship between electron orbital distance and electron energy? Rank the following general electron energies from largest to smallest electron orbital distances. Rank from largest to smallest orbital distances. ANSWER: ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 14 5/21/2014 8:02 PM Correct Excited states refer to the energy state of an electron. The higher the state, the higher the energy and the greater the distance of the electron from the nucleus. Due to the attractive force between the negatively charged electron and the positively charged nucleus, the electron requires greater energies to overcome this attraction and achieve orbits at greater distances. Concept Review: The pH Scale Can you classify solutions as acidic, neutral, or basic? Part A Decide whether each label describes a solution that is acidic, neutral, or basic, and then drag it into the appropriate bin. ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 14 5/21/2014 8:02 PM Correct Activity: Carbohydrates Click here to complete this activity. Then answer the questions. Part A Glycogen is _____. ANSWER: Correct Animals store energy in the form of glycogen. a polysaccharide found in animals a source of saturated fat a polysaccharide found in plant cell walls the form in which plants store sugars a transport protein that carries oxygen Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 14 5/21/2014 8:02 PM Part B glucose + glucose —> _____ by _____. ANSWER: Correct Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis. Part C Which of these is a source of lactose? ANSWER: Correct Lactose is the sugar found in milk. Part D Which of these is a polysaccharide? ANSWER: Correct Cellulose is a carbohydrate composed of many monomers. Part E _____ is the most abundant organic compound on Earth. ANSWER: maltose + water … dehydration synthesis lactose + water … hydrolysis starch + water … dehydration synthesis sucrose + water … dehydration synthesis cellulose + water … hydrolysis potatoes sugar beets sugar cane starch milk sucrose lactose glucose galactose cellulose Cellulose Lactose Starch Glucose Glycogen Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 14 5/21/2014 8:02 PM Correct Cellulose, a component of plant cell walls, is the most abundant organic compound found on earth. Activity: Protein Structure Click here to complete this activity. Then answer the questions. Part A Proteins are polymers of _____. ANSWER: Correct Proteins are polymers of amino acids. Part B What type of bond joins the monomers in a protein’s primary structure? ANSWER: Correct The amino acids of a protein are linked by peptide bonds. Part C Which of these illustrates the secondary structure of a protein? ANSWER: nucleotides CH2O units glycerol hydrocarbons amino acids ionic hydrogen hydrophobic S—S peptide Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 9 of 14 5/21/2014 8:02 PM Correct Alpha helices and beta pleated sheets are characteristic of a protein’s secondary structure. Part D The secondary structure of a protein results from _____. ANSWER: Correct Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges. Part E Tertiary structure is NOT directly dependent on _____. ANSWER: bonds between sulfur atoms peptide bonds hydrogen bonds hydrophobic interactions ionic bonds hydrophobic interactions ionic bonds hydrogen bonds peptide bonds bonds between sulfur atoms Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 10 of 14 5/21/2014 8:02 PM Correct Peptide bonds link together the amino acids of a protein’s primary structure. Activity: Lipids Click here to complete this activity. Then answer the questions. Part A Which of these is NOT a lipid? ANSWER: Correct RNA is a nucleic acid Part B This figure is an example of a(n) _____. ANSWER: Correct The fatty acid tails lack double bonds. steroids phospholipid RNA cholesterol wax steroid unsaturated fat nucleic acid protein saturated fat Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 11 of 14 5/21/2014 8:02 PM Part C Which of these is a phospholipid? ANSWER: Correct Phospholipids are composed of a phosphate group, a glycerol, and fatty acids. Part D Which of these is rich in unsaturated fats? ANSWER: Correct Olive oil is a plant oil, and most plant oils are rich in unsaturated fats. Part E beef fat lard butter olive oil a fat that is solid at room temperature Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 12 of 14 5/21/2014 8:02 PM A function of cholesterol that does not harm health is its role _____. ANSWER: Correct Cholesterol is an important component of animal cell membranes. Concept Review: Types of Macromolecules Can you identify characteristics of proteins, nucleic acids, and carbohydrates? Part A Decide whether each label describes proteins, nucleic acids, or carbohydrates, and then drag it into the appropriate bin. ANSWER: Correct Concept Review: Earth’s Interior Layers Can you identify characteristics of Earth’s interior layers? Part A Drag the labels to the appropriate targets. ANSWER: as a component of animal cell membranes in calcium and phosphate metabolism All of cholesterol’s effects cause the body harm. as the most abundant male sex hormone as the primary female sex hormone Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 13 of 14 5/21/2014 8:02 PM Correct Score Summary: Your score on this assignment is 99.6%. You received 31.87 out of a possible total of 32 points. Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 14 of 14 5/21/2014 8:02 PM

Chapter 03 Homework Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Components and Structure of the Atom Learning Goal: To specify the basic components of the atom and describe our modern conception of its structure. Part A The atom consists of three types of subatomic particles: protons, neutrons, and electrons. The electron is by far the lightest of the three, while the much heavier proton and neutron have masses very similar to each other. Two of the types of particles carry an electrical charge, while the third is neutral. Label the subatomic particles and appropriate charges by their relative locations. Identify the subatomic particles by dragging the appropriate labels to their respective targets. Hint 1. Which subatomic particles carry electric charge? Of the three subatomic particles, two carry equal but opposite charges. Select the two correct statements that match the subatomic particle with the appropriate charge. Check all that apply. ANSWER: Hint 2. Which subatomic particles are not found in the nucleus? Protons and electrons carry equal but opposite charges. Atomic nuclei are positively charged and are not composed of negatively charged particles. Which types of subatomic particles cannot be located within the nucleus? Select any that apply. ANSWER: ANSWER: The electron carries a positive charge. The proton carries a positive charge. The neutron carries a positive charge. The proton carries a negative charge. The electron carries a negative charge. The neutron carries a negative charge. neutrons electrons protons Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 14 5/21/2014 8:02 PM Correct This image represents the classical model of the atom proposed by Niels Bohr. Although this model has changed slightly as the result of modern scientific discoveries, it does help in understanding the relative locations of the subatomic particles in the atom. Notice that the protons and neutrons are bound in the nucleus, while the electrons are located in the space surrounding the nucleus. Part B Of the three types of subatomic particles, only neutrons do not carry charge. Protons carry a positive charge, and electrons carry a negative charge. Protons and neutrons are bound in the nucleus, while electrons orbit the nucleus. When the number of each type of subatomic particle in an atom changes, the characteristics defining the atom also change. Match the appropriate phrases with the type of subatomic particle that completes the defining characteristic. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. Hint 1. What type of subatomic particle is lost or gained when an ion forms? For any atom of a given element to go from being neutral ( ) to being ionized ( ), what type of subatomic particle must be lost or gained? Select all that apply. ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 14 5/21/2014 8:02 PM Hint 2. What type of subatomic particle identifies an element? When identifying the element classification of a particular atom, which type of subatomic particle is used? ANSWER: ANSWER: Correct The number of each type of subatomic particle plays an important role in the characteristics of the atom. The general element classification (hydrogen, carbon, oxygen, etc.) is governed by the number of protons in the nucleus. If the number of protons changes in an atom, so does the type of element. The electrons are the only type of subatomic particle not in the nucleus. They orbit around the nucleus, bound by the electromagnetic force. When electrons are lost or gained by a neutral atom, the charge balance shifts, resulting in the atom becoming an ion. Ions can be either positive when electrons are lost or negative when electrons are gained. Part C In the classical view of the atom, Bohr pictured electrons orbiting the positively charged nucleus similar to how the planets orbit the Sun. While this picture was not entirely correct, it provides a good framework in which to make calculations about the energies of electrons. Different from the predictions of Newtonian mechanics, which allows any energy to be possible, Bohr described the electron orbits (now called orbitals) as having specific energies. Rank the following electron energy states according to their electron energies. Rank from highest to lowest energies. Hint 1. What are the definitions of orbital, ground state, and excited state? Define orbital, ground state, and excited state. loss of an electron loss of a proton loss of a neutron gain of an electron gain of a proton gain of a neutron electron proton neutron Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 14 5/21/2014 8:02 PM Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. ANSWER: Hint 2. How does the state change when an electron absorbs energy? Electrons can absorb energy either from light radiation or from collisions with other atoms. If an electron is in the first excited energy state and absorbs enough energy to go to the next higher energy state, into what state will the electron transition? ANSWER: ANSWER: the ground state the second excited state the third excited state Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 14 5/21/2014 8:02 PM Correct Excited states refer to the energy of an electron. The higher the state, the higher the energy of the electron. The electron energies of each orbital are fixed. The energy required for an electron to transition between each orbital is an exact value, corresponding to the difference between the orbital energies. Any energy more or less than these precise differences cannot be used by the electron to make a transition; only the energies equal to the full values can induce a transition. Part D The Bohr model accounted for most of the general characteristics of the atom. However, the modern model based on quantum mechanics explains that, although the energy of each orbital is fixed, the orbital radius is actually an average distance. The result is a “cloud” where the electron is most likely to be located. The following is an image of an atom of hydrogen, consisting of one proton, zero neutrons, and one electron. When an electron is excited to different energy levels, the radius from the nucleus also changes. Rank the following electron energy states according to the average distance of the electron from the nucleus. Rank from largest to smallest distances. Hint 1. What is the relationship between electron orbital distance and electron energy? Rank the following general electron energies from largest to smallest electron orbital distances. Rank from largest to smallest orbital distances. ANSWER: ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 14 5/21/2014 8:02 PM Correct Excited states refer to the energy state of an electron. The higher the state, the higher the energy and the greater the distance of the electron from the nucleus. Due to the attractive force between the negatively charged electron and the positively charged nucleus, the electron requires greater energies to overcome this attraction and achieve orbits at greater distances. Concept Review: The pH Scale Can you classify solutions as acidic, neutral, or basic? Part A Decide whether each label describes a solution that is acidic, neutral, or basic, and then drag it into the appropriate bin. ANSWER: Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 14 5/21/2014 8:02 PM Correct Activity: Carbohydrates Click here to complete this activity. Then answer the questions. Part A Glycogen is _____. ANSWER: Correct Animals store energy in the form of glycogen. a polysaccharide found in animals a source of saturated fat a polysaccharide found in plant cell walls the form in which plants store sugars a transport protein that carries oxygen Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 14 5/21/2014 8:02 PM Part B glucose + glucose —> _____ by _____. ANSWER: Correct Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis. Part C Which of these is a source of lactose? ANSWER: Correct Lactose is the sugar found in milk. Part D Which of these is a polysaccharide? ANSWER: Correct Cellulose is a carbohydrate composed of many monomers. Part E _____ is the most abundant organic compound on Earth. ANSWER: maltose + water … dehydration synthesis lactose + water … hydrolysis starch + water … dehydration synthesis sucrose + water … dehydration synthesis cellulose + water … hydrolysis potatoes sugar beets sugar cane starch milk sucrose lactose glucose galactose cellulose Cellulose Lactose Starch Glucose Glycogen Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 8 of 14 5/21/2014 8:02 PM Correct Cellulose, a component of plant cell walls, is the most abundant organic compound found on earth. Activity: Protein Structure Click here to complete this activity. Then answer the questions. Part A Proteins are polymers of _____. ANSWER: Correct Proteins are polymers of amino acids. Part B What type of bond joins the monomers in a protein’s primary structure? ANSWER: Correct The amino acids of a protein are linked by peptide bonds. Part C Which of these illustrates the secondary structure of a protein? ANSWER: nucleotides CH2O units glycerol hydrocarbons amino acids ionic hydrogen hydrophobic S—S peptide Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 9 of 14 5/21/2014 8:02 PM Correct Alpha helices and beta pleated sheets are characteristic of a protein’s secondary structure. Part D The secondary structure of a protein results from _____. ANSWER: Correct Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges. Part E Tertiary structure is NOT directly dependent on _____. ANSWER: bonds between sulfur atoms peptide bonds hydrogen bonds hydrophobic interactions ionic bonds hydrophobic interactions ionic bonds hydrogen bonds peptide bonds bonds between sulfur atoms Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 10 of 14 5/21/2014 8:02 PM Correct Peptide bonds link together the amino acids of a protein’s primary structure. Activity: Lipids Click here to complete this activity. Then answer the questions. Part A Which of these is NOT a lipid? ANSWER: Correct RNA is a nucleic acid Part B This figure is an example of a(n) _____. ANSWER: Correct The fatty acid tails lack double bonds. steroids phospholipid RNA cholesterol wax steroid unsaturated fat nucleic acid protein saturated fat Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 11 of 14 5/21/2014 8:02 PM Part C Which of these is a phospholipid? ANSWER: Correct Phospholipids are composed of a phosphate group, a glycerol, and fatty acids. Part D Which of these is rich in unsaturated fats? ANSWER: Correct Olive oil is a plant oil, and most plant oils are rich in unsaturated fats. Part E beef fat lard butter olive oil a fat that is solid at room temperature Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 12 of 14 5/21/2014 8:02 PM A function of cholesterol that does not harm health is its role _____. ANSWER: Correct Cholesterol is an important component of animal cell membranes. Concept Review: Types of Macromolecules Can you identify characteristics of proteins, nucleic acids, and carbohydrates? Part A Decide whether each label describes proteins, nucleic acids, or carbohydrates, and then drag it into the appropriate bin. ANSWER: Correct Concept Review: Earth’s Interior Layers Can you identify characteristics of Earth’s interior layers? Part A Drag the labels to the appropriate targets. ANSWER: as a component of animal cell membranes in calcium and phosphate metabolism All of cholesterol’s effects cause the body harm. as the most abundant male sex hormone as the primary female sex hormone Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 13 of 14 5/21/2014 8:02 PM Correct Score Summary: Your score on this assignment is 99.6%. You received 31.87 out of a possible total of 32 points. Chapter 03 Homework http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 14 of 14 5/21/2014 8:02 PM

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Phy 2201 page – 1 – Physics 2201 Homework III part 2. Fall 2015. Due: Tuesday November 17, 2015 Show all work with clear setup and/or explain all answers. All solutions must be based on work and/or energy methods. 10 points each. Partial credit is available. 1) A 1.4 kg falling object (subject to the effects of aerodynamic drag) is 1800 m high, traveling at 34 m/s and has not yet reached terminal speed. It first reaches terminal speed at a height of 1340 m and the terminal speed is 37.3 m/s. a) Determine if the mechanical energy ( ? E = K +Ug ) of the system consisting of the falling object and Earth’s gravity field has been conserved during the fall from 1800 m to 500 m. b) How much work (if any) including the correct sign (+ or -­‐) has been done on the system over this interval (presumably by the external drag force)? c) Will the energy of the system consisting of the object, the gravity field and the surrounding air be conserved over this interval? Explain your answer. Is there an additional energy that must be accounted for in this analysis? What is it and how much of it has been generated? Note: terminal speed is a constant speed. 2) The 0.2 kg box below slides down a curved ramp, jumps a small gap and lands on a flat platform. At the point on the ramp shown it is 1.5 m above the floor and its speed is 2.0 m/s. At the point shown on the platform the box is 0.4 m above the floor and sliding at 4.2 m/s. a) If we consider a system consisting of the box and Earth’s gravity field so that ? E = K +Ug , has the energy of this system been conserved during the described process? Explain how you know. b) If we consider the exact same process but broaden our system definition so that ? E = K +Ug + Eother and ? Eother includes any “other” form of energy that might have been produced through the process (most of it is thermal), what objects are included in this system? Discuss, don’t just state a list. c) Determine ? ΔEother for the process as described. d) How much kinetic energy would the box have on the platform if ? ΔEother = 0 ? Phy 2201 page – 2 – 3) The system below consists of two masses attached through a string of negligible mass over a pulley that turns with negligible friction. ? m1 > m2 and the sphere ? m2 is immersed in a viscous fluid that exerts a considerable drag force. Starting from rest the system is set into motion by releasing ? m1 which causes this mass to descend while the other rises (assume the string instantly becomes taut). In what follows analyze the motion by defining the “system” as both masses and Earth’s gravity field. a) Once released each mass travels a distance ? h1 and somewhere during this interval both masses reach terminal speed ? VT . Write out (derive/formulate) a mathematical expression for the change of the potential energy of the system over this interval (Using the givens! Don’t make up numbers or define your own variable names.) Has the system gained or lost potential energy? Explain how you know. b) Write out (derive/formulate) a mathematical expression for the change in the kinetic energy of the system over the ? h1 interval (using the givens). Write out an expression for the work done by the drag force over this interval using the givens. c) Following the ? h1 interval the system moves a distance ? h2 while the sphere is still immersed in the fluid. Write out an expression for the work done by the drag force over this interval. Can you tell from this expression if the work done by drag is positive or negative? (You should.) Which is it and how do you know? d) If ? h1 = h2 over which interval does the drag force do more work in an absolute value sense? How do you know? Phy 2201 page – 3 – 4) A 48 kg diver jumps off a cliff (with a running start) into the ocean. The cliff is 50 m above the ocean below. Her coach, using a video of the dive, determines that at a point in flight when she has risen 0.7 m above the cliff, her speed1 (center of mass) is 0.5 m/s. Frictional effects such as drag are negligible. Formulate your solution using the diver and Earth’s gravity field as a system. Gravity does not do work on this system. It’s effects are captured in changes in potential energy. a) How much kinetic energy did she have at takeoff? What was her speed? b) How much kinetic energy will she have as she splashes into the ocean? c) What minimum amount of chemical energy needed to be consumed within the diver’s body in order for her to walk to the cliff, from ocean level, and then take off (jump)? Explain how you know. 1 Includes both x and y velocity components. This is not the highest point in the jump.

Phy 2201 page – 1 – Physics 2201 Homework III part 2. Fall 2015. Due: Tuesday November 17, 2015 Show all work with clear setup and/or explain all answers. All solutions must be based on work and/or energy methods. 10 points each. Partial credit is available. 1) A 1.4 kg falling object (subject to the effects of aerodynamic drag) is 1800 m high, traveling at 34 m/s and has not yet reached terminal speed. It first reaches terminal speed at a height of 1340 m and the terminal speed is 37.3 m/s. a) Determine if the mechanical energy ( ? E = K +Ug ) of the system consisting of the falling object and Earth’s gravity field has been conserved during the fall from 1800 m to 500 m. b) How much work (if any) including the correct sign (+ or -­‐) has been done on the system over this interval (presumably by the external drag force)? c) Will the energy of the system consisting of the object, the gravity field and the surrounding air be conserved over this interval? Explain your answer. Is there an additional energy that must be accounted for in this analysis? What is it and how much of it has been generated? Note: terminal speed is a constant speed. 2) The 0.2 kg box below slides down a curved ramp, jumps a small gap and lands on a flat platform. At the point on the ramp shown it is 1.5 m above the floor and its speed is 2.0 m/s. At the point shown on the platform the box is 0.4 m above the floor and sliding at 4.2 m/s. a) If we consider a system consisting of the box and Earth’s gravity field so that ? E = K +Ug , has the energy of this system been conserved during the described process? Explain how you know. b) If we consider the exact same process but broaden our system definition so that ? E = K +Ug + Eother and ? Eother includes any “other” form of energy that might have been produced through the process (most of it is thermal), what objects are included in this system? Discuss, don’t just state a list. c) Determine ? ΔEother for the process as described. d) How much kinetic energy would the box have on the platform if ? ΔEother = 0 ? Phy 2201 page – 2 – 3) The system below consists of two masses attached through a string of negligible mass over a pulley that turns with negligible friction. ? m1 > m2 and the sphere ? m2 is immersed in a viscous fluid that exerts a considerable drag force. Starting from rest the system is set into motion by releasing ? m1 which causes this mass to descend while the other rises (assume the string instantly becomes taut). In what follows analyze the motion by defining the “system” as both masses and Earth’s gravity field. a) Once released each mass travels a distance ? h1 and somewhere during this interval both masses reach terminal speed ? VT . Write out (derive/formulate) a mathematical expression for the change of the potential energy of the system over this interval (Using the givens! Don’t make up numbers or define your own variable names.) Has the system gained or lost potential energy? Explain how you know. b) Write out (derive/formulate) a mathematical expression for the change in the kinetic energy of the system over the ? h1 interval (using the givens). Write out an expression for the work done by the drag force over this interval using the givens. c) Following the ? h1 interval the system moves a distance ? h2 while the sphere is still immersed in the fluid. Write out an expression for the work done by the drag force over this interval. Can you tell from this expression if the work done by drag is positive or negative? (You should.) Which is it and how do you know? d) If ? h1 = h2 over which interval does the drag force do more work in an absolute value sense? How do you know? Phy 2201 page – 3 – 4) A 48 kg diver jumps off a cliff (with a running start) into the ocean. The cliff is 50 m above the ocean below. Her coach, using a video of the dive, determines that at a point in flight when she has risen 0.7 m above the cliff, her speed1 (center of mass) is 0.5 m/s. Frictional effects such as drag are negligible. Formulate your solution using the diver and Earth’s gravity field as a system. Gravity does not do work on this system. It’s effects are captured in changes in potential energy. a) How much kinetic energy did she have at takeoff? What was her speed? b) How much kinetic energy will she have as she splashes into the ocean? c) What minimum amount of chemical energy needed to be consumed within the diver’s body in order for her to walk to the cliff, from ocean level, and then take off (jump)? Explain how you know. 1 Includes both x and y velocity components. This is not the highest point in the jump.

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Question 1 When using NTFS as a file system, what can be used to control the amount of hard disk space each user on the machine can have as a maximum? Answer Logical drives Extended partitions Disk quotas Security Center Question 2 Pin 1 of the floppy cable connects to pin 34 of the controller. Answer True False Question 3 What is the primary cause of hard drive failures? Answer Heat Dust Dirty laser lens Moving parts Question 4 The DBR contains the system files. Answer True False Question 5 A spanned volume requires a minimum of three hard drives. Answer True False Question 6 Which situation would not be appropriate for the use of SSDs? Answer A military operation where fast access to data is critical A medical imaging office that needs high-capacity storage A manufacturing plant with heat-sensitive equipment A research facility where noise must be kept to a minimum Question 7 Why are SSDs more susceptible than mechanical hard drives to electrostatic discharge? Answer The internal battery of the SSD provides additional current. SSDs are memory. The voltage level of the SSD is lower than a mechanical hard drive. The SSD is a more fragile component. Question 8 A motherboard has two PATA IDE connectors, A and B. A is nearer the edge than B. The IDE cable from A connects to a 500GB hard drive and then to a 200GB hard drive. The IDE cable from B connects to an R/W optical drive and then to a Blu-ray optical drive. Assuming the setup is optimal, which of the following describes the 500GB hard drive? Answer Primary slave Secondary slave Primary master Secondary master Question 9 The primary IDE motherboard connection normally uses I/O address 1F0 -1F7h and IRQ 15. Answer True False Question 10 A cable with a twist is used when installing two floppy drives. Answer True False Question 11 What does partitioning the hard drive mean? Answer Dividing the hard drive up into three different sections: one for each type of file system Preparing the drive to be mounted Giving the hard drive a drive letter and/or allowing the hard drive to be seen as more than one drive Preparing the drive for an operating system Question 12 The Network Engineering Technology departmental secretary is getting a new computer funded by a grant. The old computer is being moved by the PC technicians to give to the new program facilitator in another department. Which one of the following is most likely to be used before the program facilitator uses the computer? Answer Check Now Tool Backup Tool Disk Management Tool BitLocker Question 13 What is CHKDSK? Answer A command used to scan the disk for viruses during off hours A program used to defragment the hard drive A program used to locate and identify lost clusters A command used to verify the validity of the drive surface before installing a file system or an operating system Question 14 When a disk has been prepared to store data, it has been Answer Cleaned Tracked Enabled Formatted Question 15 Where would you go to enable a SATA port? Answer CMOS BIOS Disk Management Tool Task Manager Question 16 The Windows boot partition is the partition that must contain the majority of the operating system. Answer True False Question 17 Two considerations when adding or installing a floppy drive are an available drive bay and an available power connector. Answer True False Question 18 What is the difference between a SATA 2 and a SATA 3 hard drive? Answer The SATA 3 has a different power connector. The SATA 3 device transmits more simultaneous bits than SATA 2. The SATA 3 device transmits data faster. SATA 3 will always be a larger capacity drive. The SATA 3 device will be physically smaller. Question 19 What command would be used in Windows 7 to repair a partition table? Answer FDISK FORMAT FIXBOOT bootrec /FixMbr FIXMBR Question 20 What file system is optimized for optical media? Answer exFAT FAT32 CDFS NTFS Question 21 One of the most effective ways of increasing computer performance is to increase the size of virtual memory. Answer True False Question 22 Older PATA IDE cables and the Ultra ATA/66 cable differ by Answer Where the twist occurs The number of conductors The number of pins The number of devices they can connect to Question 23 Which of the following is NOT important in assigning SCSI IDs? Answer The hard drive that the system boots to may have a preset ID. ID priority must match the order of appearance on the SCSI chain. All devices must have unique IDs. Slower devices should have higher priority IDs. Question 24 The ATA standard is associated with the SCSI interface. Answer True False Question 25 A striped volume requires a minimum of two hard drives. Answer True False

Question 1 When using NTFS as a file system, what can be used to control the amount of hard disk space each user on the machine can have as a maximum? Answer Logical drives Extended partitions Disk quotas Security Center Question 2 Pin 1 of the floppy cable connects to pin 34 of the controller. Answer True False Question 3 What is the primary cause of hard drive failures? Answer Heat Dust Dirty laser lens Moving parts Question 4 The DBR contains the system files. Answer True False Question 5 A spanned volume requires a minimum of three hard drives. Answer True False Question 6 Which situation would not be appropriate for the use of SSDs? Answer A military operation where fast access to data is critical A medical imaging office that needs high-capacity storage A manufacturing plant with heat-sensitive equipment A research facility where noise must be kept to a minimum Question 7 Why are SSDs more susceptible than mechanical hard drives to electrostatic discharge? Answer The internal battery of the SSD provides additional current. SSDs are memory. The voltage level of the SSD is lower than a mechanical hard drive. The SSD is a more fragile component. Question 8 A motherboard has two PATA IDE connectors, A and B. A is nearer the edge than B. The IDE cable from A connects to a 500GB hard drive and then to a 200GB hard drive. The IDE cable from B connects to an R/W optical drive and then to a Blu-ray optical drive. Assuming the setup is optimal, which of the following describes the 500GB hard drive? Answer Primary slave Secondary slave Primary master Secondary master Question 9 The primary IDE motherboard connection normally uses I/O address 1F0 -1F7h and IRQ 15. Answer True False Question 10 A cable with a twist is used when installing two floppy drives. Answer True False Question 11 What does partitioning the hard drive mean? Answer Dividing the hard drive up into three different sections: one for each type of file system Preparing the drive to be mounted Giving the hard drive a drive letter and/or allowing the hard drive to be seen as more than one drive Preparing the drive for an operating system Question 12 The Network Engineering Technology departmental secretary is getting a new computer funded by a grant. The old computer is being moved by the PC technicians to give to the new program facilitator in another department. Which one of the following is most likely to be used before the program facilitator uses the computer? Answer Check Now Tool Backup Tool Disk Management Tool BitLocker Question 13 What is CHKDSK? Answer A command used to scan the disk for viruses during off hours A program used to defragment the hard drive A program used to locate and identify lost clusters A command used to verify the validity of the drive surface before installing a file system or an operating system Question 14 When a disk has been prepared to store data, it has been Answer Cleaned Tracked Enabled Formatted Question 15 Where would you go to enable a SATA port? Answer CMOS BIOS Disk Management Tool Task Manager Question 16 The Windows boot partition is the partition that must contain the majority of the operating system. Answer True False Question 17 Two considerations when adding or installing a floppy drive are an available drive bay and an available power connector. Answer True False Question 18 What is the difference between a SATA 2 and a SATA 3 hard drive? Answer The SATA 3 has a different power connector. The SATA 3 device transmits more simultaneous bits than SATA 2. The SATA 3 device transmits data faster. SATA 3 will always be a larger capacity drive. The SATA 3 device will be physically smaller. Question 19 What command would be used in Windows 7 to repair a partition table? Answer FDISK FORMAT FIXBOOT bootrec /FixMbr FIXMBR Question 20 What file system is optimized for optical media? Answer exFAT FAT32 CDFS NTFS Question 21 One of the most effective ways of increasing computer performance is to increase the size of virtual memory. Answer True False Question 22 Older PATA IDE cables and the Ultra ATA/66 cable differ by Answer Where the twist occurs The number of conductors The number of pins The number of devices they can connect to Question 23 Which of the following is NOT important in assigning SCSI IDs? Answer The hard drive that the system boots to may have a preset ID. ID priority must match the order of appearance on the SCSI chain. All devices must have unique IDs. Slower devices should have higher priority IDs. Question 24 The ATA standard is associated with the SCSI interface. Answer True False Question 25 A striped volume requires a minimum of two hard drives. Answer True False

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Assignment 8 Due: 11:59pm on Friday, April 4, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 10.3 Part A If a particle’s speed increases by a factor of 5, by what factor does its kinetic energy change? ANSWER: Correct Conceptual Question 10.11 A spring is compressed 1.5 . Part A How far must you compress a spring with twice the spring constant to store the same amount of energy? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct = 25 K2 K1 cm x = 1.1 cm Problem 10.2 The lowest point in Death Valley is below sea level. The summit of nearby Mt. Whitney has an elevation of 4420 . Part A What is the change in potential energy of an energetic 80 hiker who makes it from the floor of Death Valley to the top of Mt.Whitney? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 10.3 Part A At what speed does a 1800 compact car have the same kinetic energy as a 1.80×104 truck going 21.0 ? Express your answer with the appropriate units. ANSWER: Correct Problem 10.5 A boy reaches out of a window and tosses a ball straight up with a speed of 13 . The ball is 21 above the ground as he releases it. 85m m kg U = 3.5×106 J kg kg km/hr vc = 66.4 km hr m/s m Part A Use energy to find the ball’s maximum height above the ground. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B Use energy to find the ball’s speed as it passes the window on its way down. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C Use energy to find the speed of impact on the ground. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Hmax = 30 m v = 13 ms v = 24 ms Problem 10.8 A 59.0 skateboarder wants to just make it to the upper edge of a “quarter pipe,” a track that is one-quarter of a circle with a radius of 2.30 . Part A What speed does he need at the bottom? Express your answer with the appropriate units. ANSWER: Correct Problem 10.12 A 1500 car traveling at 12 suddenly runs out of gas while approaching the valley shown in the figure. The alert driver immediately puts the car in neutral so that it will roll. Part A kg m 6.71 ms kg m/s What will be the car’s speed as it coasts into the gas station on the other side of the valley? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Ups and Downs Learning Goal: To apply the law of conservation of energy to an object launched upward in the gravitational field of the earth. In the absence of nonconservative forces such as friction and air resistance, the total mechanical energy in a closed system is conserved. This is one particular case of the law of conservation of energy. In this problem, you will apply the law of conservation of energy to different objects launched from the earth. The energy transformations that take place involve the object’s kinetic energy and its gravitational potential energy . The law of conservation of energy for such cases implies that the sum of the object’s kinetic energy and potential energy does not change with time. This idea can be expressed by the equation , where “i” denotes the “initial” moment and “f” denotes the “final” moment. Since any two moments will work, the choice of the moments to consider is, technically, up to you. That choice, though, is usually suggested by the question posed in the problem. First, let us consider an object launched vertically upward with an initial speed . Neglect air resistance. Part A As the projectile goes upward, what energy changes take place? ANSWER: v = 6.8 ms K = (1/2)mv2 U = mgh Ki + Ui = Kf + Uf v Correct Part B At the top point of the flight, what can be said about the projectile’s kinetic and potential energy? ANSWER: Correct Strictly speaking, it is not the ball that possesses potential energy; rather, it is the system “Earth-ball.” Although we will often talk about “the gravitational potential energy of an elevated object,” it is useful to keep in mind that the energy, in fact, is associated with the interactions between the earth and the elevated object. Part C The potential energy of the object at the moment of launch __________. ANSWER: Both kinetic and potential energy decrease. Both kinetic and potential energy increase. Kinetic energy decreases; potential energy increases. Kinetic energy increases; potential energy decreases. Both kinetic and potential energy are at their maximum values. Both kinetic and potential energy are at their minimum values. Kinetic energy is at a maximum; potential energy is at a minimum. Kinetic energy is at a minimum; potential energy is at a maximum. Correct Usually, the zero level is chosen so as to make the relevant calculations simpler. In this case, it makes good sense to assume that at the ground level–but this is not, by any means, the only choice! Part D Using conservation of energy, find the maximum height to which the object will rise. Express your answer in terms of and the magnitude of the acceleration of gravity . ANSWER: Correct You may remember this result from kinematics. It is comforting to know that our new approach yields the same answer. Part E At what height above the ground does the projectile have a speed of ? Express your answer in terms of and the magnitude of the acceleration of gravity . ANSWER: is negative is positive is zero depends on the choice of the “zero level” of potential energy U = 0 hmax v g hmax = v2 2g h 0.5v v g h = 3 v2 8g Correct Part F What is the speed of the object at the height of ? Express your answer in terms of and . Use three significant figures in the numeric coefficient. Hint 1. How to approach the problem You are being asked for the speed at half of the maximum height. You know that at the initial height ( ), the speed is . All of the energy is kinetic energy, and so, the total energy is . At the maximum height, all of the energy is potential energy. Since the gravitational potential energy is proportional to , half of the initial kinetic energy must have been converted to potential energy when the projectile is at . Thus, the kinetic energy must be half of its original value (i.e., when ). You need to determine the speed, as a multiple of , that corresponds to such a kinetic energy. ANSWER: Correct Let us now consider objects launched at an angle. For such situations, using conservation of energy leads to a quicker solution than can be produced by kinematics. Part G A ball is launched as a projectile with initial speed at an angle above the horizontal. Using conservation of energy, find the maximum height of the ball’s flight. Express your answer in terms of , , and . Hint 1. Find the final kinetic energy Find the final kinetic energy of the ball. Here, the best choice of “final” moment is the point at which the ball reaches its maximum height, since this is the point we are interested in. u (1/2)hmax v g h = 0 v (1/2)mv2 h (1/2)hmax (1/4)mv2 h = (1/2)hmax v u = 0.707v v hmax v g Kf Express your answer in terms of , , and . Hint 1. Find the speed at the maximum height The speed of the ball at the maximum height is __________. ANSWER: ANSWER: ANSWER: Correct Part H A ball is launched with initial speed from ground level up a frictionless slope. The slope makes an angle with the horizontal. Using conservation of energy, find the maximum vertical height to which the ball will climb. Express your answer in terms of , , and . You may or may not use all of these quantities. v m 0 v v cos v sin v tan Kf = 0.5m(vcos( ))2 hmax = (vsin( ))2 2g v hmax v g ANSWER: Correct Interestingly, the answer does not depend on . The difference between this situation and the projectile case is that the ball moving up a slope has no kinetic energy at the top of its trajectory whereas the projectile launched at an angle does. Part I A ball is launched with initial speed from the ground level up a frictionless hill. The hill becomes steeper as the ball slides up; however, the ball remains in contact with the hill at all times. Using conservation of energy, find the maximum vertical height to which the ball will climb. Express your answer in terms of and . ANSWER: Correct The profile of the hill does not matter; the equation would have the same terms regardless of the steepness of the hill. Problem 10.14 A 12- -long spring is attached to the ceiling. When a 2.2 mass is hung from it, the spring stretches to a length of 17 . Part A What is the spring constant ? Express your answer to two significant figures and include the appropriate units. hmax = v2 2g v hmax v g hmax = v2 2g Ki + Ui = Kf + Uf cm kg cm k ANSWER: Correct Part B How long is the spring when a 3.0 mass is suspended from it? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Enhanced EOC: Problem 10.17 A 6.2 mass hanging from a spring scale is slowly lowered onto a vertical spring, as shown in . You may want to review ( pages 255 – 257) . For help with math skills, you may want to review: Solving Algebraic Equations = 430 k Nm kg y = 19 cm kg Part A What does the spring scale read just before the mass touches the lower spring? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces acting on the mass before it touches the scale. What is the net force on the mass? What is the force on the mass due to gravity? What is the force on the mass due to the scale? ANSWER: Correct Part B The scale reads 22 when the lower spring has been compressed by 2.7 . What is the value of the spring constant for the lower spring? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces acting on the mass. What is the net force on the mass? What is the force on the mass due to gravity? What is the force on the mass due to the scale? Use these to determine the force on the mass by the spring, taking note of the directions from your picture. How is the spring constant related to the force by the spring and the compression of the spring? Check your units. ANSWER: F = 61 N N cm k = 1400 k Nm Correct Part C At what compression length will the scale read zero? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces on the mass. When the scale reads zero, what is the force on the mass due to the scale? What is the gravitational force on the mass? What is the force on the mass by the spring? How is the compression length related to the force by the spring and the spring constant? Check your units. ANSWER: Correct Problem 10.18 Part A How far must you stretch a spring with = 800 to store 180 of energy? Express your answer to two significant figures and include the appropriate units. ANSWER: y = 4.2 cm k N/m J Correct Problem 10.22 A 15 runaway grocery cart runs into a spring with spring constant 230 and compresses it by 57 . Part A What was the speed of the cart just before it hit the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Spring Gun A spring-loaded toy gun is used to shoot a ball straight up in the air. The ball reaches a maximum height , measured from the equilibrium position of the spring. s = 0.67 m kg N/m cm v = 2.2 ms H Part A The same ball is shot straight up a second time from the same gun, but this time the spring is compressed only half as far before firing. How far up does the ball go this time? Neglect friction. Assume that the spring is ideal and that the distance by which the spring is compressed is negligible compared to . Hint 1. Potential energy of the spring The potential energy of a spring is proportional to the square of the distance the spring is compressed. The spring was compressed half the distance, so the mass, when launched, has one quarter of the energy as in the first trial. Hint 2. Potential energy of the ball At the highest point in the ball’s trajectory, all of the spring’s potential energy has been converted into gravitational potential energy of the ball. ANSWER: Correct A Bullet Is Fired into a Wooden Block A bullet of mass is fired horizontally with speed at a wooden block of mass resting on a frictionless table. The bullet hits the block and becomes completely embedded within it. After the bullet has come to rest within the block, the block, with the bullet in it, is traveling at speed . H height = H 4 mb vi mw vf Part A Which of the following best describes this collision? Hint 1. Types of collisions An inelastic collision is a collision in which kinetic energy is not conserved. In a partially inelastic collision, kinetic energy is lost, but the objects colliding do not stick together. From this information, you can infer what completely inelastic and elastic collisions are. ANSWER: Correct Part B Which of the following quantities, if any, are conserved during this collision? Hint 1. When is kinetic energy conserved? Kinetic energy is conserved only in perfectly elastic collisions. ANSWER: perfectly elastic partially inelastic perfectly inelastic Correct Part C What is the speed of the block/bullet system after the collision? Express your answer in terms of , , and . Hint 1. Find the momentum after the collision What is the total momentum of the block/bullet system after the collision? Express your answer in terms of and other given quantities. ANSWER: Hint 2. Use conservation of momentum The momentum of the block/bullet system is conserved. Therefore, the momentum before the collision is the same as the momentum after the collision. Find a second expression for , this time expressed as the total momentum of the system before the collision. Express your answer in terms of and other given quantities. ANSWER: kinetic energy only momentum only kinetic energy and momentum neither momentum nor kinetic energy vi mw mb ptotal vf ptotal = (mw + mb)vf ptotal vi ptotal = mbvi ANSWER: Correct Problem 10.31 Ball 1, with a mass of 150 and traveling at 15.0 , collides head on with ball 2, which has a mass of 340 and is initially at rest. Part A What are the final velocities of each ball if the collision is perfectly elastic? Express your answer with the appropriate units. ANSWER: Correct Part B Express your answer with the appropriate units. ANSWER: Correct Part C vf = mb vi mb+mw g m/s g (vfx) = -5.82 1 ms (vfx) = 9.18 2 ms What are the final velocities of each ball if the collision is perfectly inelastic? Express your answer with the appropriate units. ANSWER: Correct Part D Express your answer with the appropriate units. ANSWER: Correct Enhanced EOC: Problem 10.43 A package of mass is released from rest at a warehouse loading dock and slides down the = 2.2 – high, frictionless chute to a waiting truck. Unfortunately, the truck driver went on a break without having removed the previous package, of mass , from the bottom of the chute. You may want to review ( pages 265 – 269) . For help with math skills, you may want to review: Solving Algebraic Equations (vfx) = 4.59 1 ms (vfx) = 4.59 2 ms m h m 2m Part A Suppose the packages stick together. What is their common speed after the collision? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem There are two parts to this problem: the block sliding down the frictionless incline and the collision. What conservation laws are valid in each part? In terms of , what are the kinetic and potential energies of the block at the top of the incline? What is the potential energy of the same block at the bottom just before the collision? What are the kinetic energy and velocity of block just before the collision? What is conserved during the collision? What is the total momentum of the two blocks before the collision? What is the momentum of the two blocks stuck together after the collision? What is the velocity of the two blocks after the collision? ANSWER: Correct Part B Suppose the collision between the packages is perfectly elastic. To what height does the package of mass rebound? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem There are three parts to this problem: the block sliding down the incline, the collision, and mass going back up the incline. What conservation laws are valid in each part? m m v = 2.2 ms m m What is an elastic collision? For an elastic collision, how are the initial and final velocities related when one of the masses is initially at rest? Using the velocity of just before the collision from Part A, what is the velocity of just after the collision in this case? What are the kinetic and potential energies of mass just after the collision? What is the kinetic energy of mass at its maximum rebound height? Using conservation of energy, what is the potential energy of mass at its maximum height? What is the maximum height? ANSWER: Correct Problem 10.35 A cannon tilted up at a 35.0 angle fires a cannon ball at 79.0 from atop a 21.0 -high fortress wall. Part A What is the ball’s impact speed on the ground below? Express your answer with the appropriate units. ANSWER: Correct Problem 10.45 A 1000 safe is 2.5 above a heavy-duty spring when the rope holding the safe breaks. The safe hits the spring and compresses it 48 . m m m m m h = 24 cm $ m/s m vf = 81.6 ms kg m cm Part A What is the spring constant of the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 10.49 A 100 block on a frictionless table is firmly attached to one end of a spring with = 21 . The other end of the spring is anchored to the wall. A 30 ball is thrown horizontally toward the block with a speed of 6.0 . Part A If the collision is perfectly elastic, what is the ball’s speed immediately after the collision? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the maximum compression of the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: = 2.5×105 k Nm g k N/m g m/s v = 3.2 ms Correct Part C Repeat part A for the case of a perfectly inelastic collision. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D Repeat part B for the case of a perfectly inelastic collision. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 99.4%. You received 120.28 out of a possible total of 121 points. x = 0.19 m v = 1.4 ms x = 0.11 m

Assignment 8 Due: 11:59pm on Friday, April 4, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 10.3 Part A If a particle’s speed increases by a factor of 5, by what factor does its kinetic energy change? ANSWER: Correct Conceptual Question 10.11 A spring is compressed 1.5 . Part A How far must you compress a spring with twice the spring constant to store the same amount of energy? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct = 25 K2 K1 cm x = 1.1 cm Problem 10.2 The lowest point in Death Valley is below sea level. The summit of nearby Mt. Whitney has an elevation of 4420 . Part A What is the change in potential energy of an energetic 80 hiker who makes it from the floor of Death Valley to the top of Mt.Whitney? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 10.3 Part A At what speed does a 1800 compact car have the same kinetic energy as a 1.80×104 truck going 21.0 ? Express your answer with the appropriate units. ANSWER: Correct Problem 10.5 A boy reaches out of a window and tosses a ball straight up with a speed of 13 . The ball is 21 above the ground as he releases it. 85m m kg U = 3.5×106 J kg kg km/hr vc = 66.4 km hr m/s m Part A Use energy to find the ball’s maximum height above the ground. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B Use energy to find the ball’s speed as it passes the window on its way down. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C Use energy to find the speed of impact on the ground. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Hmax = 30 m v = 13 ms v = 24 ms Problem 10.8 A 59.0 skateboarder wants to just make it to the upper edge of a “quarter pipe,” a track that is one-quarter of a circle with a radius of 2.30 . Part A What speed does he need at the bottom? Express your answer with the appropriate units. ANSWER: Correct Problem 10.12 A 1500 car traveling at 12 suddenly runs out of gas while approaching the valley shown in the figure. The alert driver immediately puts the car in neutral so that it will roll. Part A kg m 6.71 ms kg m/s What will be the car’s speed as it coasts into the gas station on the other side of the valley? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Ups and Downs Learning Goal: To apply the law of conservation of energy to an object launched upward in the gravitational field of the earth. In the absence of nonconservative forces such as friction and air resistance, the total mechanical energy in a closed system is conserved. This is one particular case of the law of conservation of energy. In this problem, you will apply the law of conservation of energy to different objects launched from the earth. The energy transformations that take place involve the object’s kinetic energy and its gravitational potential energy . The law of conservation of energy for such cases implies that the sum of the object’s kinetic energy and potential energy does not change with time. This idea can be expressed by the equation , where “i” denotes the “initial” moment and “f” denotes the “final” moment. Since any two moments will work, the choice of the moments to consider is, technically, up to you. That choice, though, is usually suggested by the question posed in the problem. First, let us consider an object launched vertically upward with an initial speed . Neglect air resistance. Part A As the projectile goes upward, what energy changes take place? ANSWER: v = 6.8 ms K = (1/2)mv2 U = mgh Ki + Ui = Kf + Uf v Correct Part B At the top point of the flight, what can be said about the projectile’s kinetic and potential energy? ANSWER: Correct Strictly speaking, it is not the ball that possesses potential energy; rather, it is the system “Earth-ball.” Although we will often talk about “the gravitational potential energy of an elevated object,” it is useful to keep in mind that the energy, in fact, is associated with the interactions between the earth and the elevated object. Part C The potential energy of the object at the moment of launch __________. ANSWER: Both kinetic and potential energy decrease. Both kinetic and potential energy increase. Kinetic energy decreases; potential energy increases. Kinetic energy increases; potential energy decreases. Both kinetic and potential energy are at their maximum values. Both kinetic and potential energy are at their minimum values. Kinetic energy is at a maximum; potential energy is at a minimum. Kinetic energy is at a minimum; potential energy is at a maximum. Correct Usually, the zero level is chosen so as to make the relevant calculations simpler. In this case, it makes good sense to assume that at the ground level–but this is not, by any means, the only choice! Part D Using conservation of energy, find the maximum height to which the object will rise. Express your answer in terms of and the magnitude of the acceleration of gravity . ANSWER: Correct You may remember this result from kinematics. It is comforting to know that our new approach yields the same answer. Part E At what height above the ground does the projectile have a speed of ? Express your answer in terms of and the magnitude of the acceleration of gravity . ANSWER: is negative is positive is zero depends on the choice of the “zero level” of potential energy U = 0 hmax v g hmax = v2 2g h 0.5v v g h = 3 v2 8g Correct Part F What is the speed of the object at the height of ? Express your answer in terms of and . Use three significant figures in the numeric coefficient. Hint 1. How to approach the problem You are being asked for the speed at half of the maximum height. You know that at the initial height ( ), the speed is . All of the energy is kinetic energy, and so, the total energy is . At the maximum height, all of the energy is potential energy. Since the gravitational potential energy is proportional to , half of the initial kinetic energy must have been converted to potential energy when the projectile is at . Thus, the kinetic energy must be half of its original value (i.e., when ). You need to determine the speed, as a multiple of , that corresponds to such a kinetic energy. ANSWER: Correct Let us now consider objects launched at an angle. For such situations, using conservation of energy leads to a quicker solution than can be produced by kinematics. Part G A ball is launched as a projectile with initial speed at an angle above the horizontal. Using conservation of energy, find the maximum height of the ball’s flight. Express your answer in terms of , , and . Hint 1. Find the final kinetic energy Find the final kinetic energy of the ball. Here, the best choice of “final” moment is the point at which the ball reaches its maximum height, since this is the point we are interested in. u (1/2)hmax v g h = 0 v (1/2)mv2 h (1/2)hmax (1/4)mv2 h = (1/2)hmax v u = 0.707v v hmax v g Kf Express your answer in terms of , , and . Hint 1. Find the speed at the maximum height The speed of the ball at the maximum height is __________. ANSWER: ANSWER: ANSWER: Correct Part H A ball is launched with initial speed from ground level up a frictionless slope. The slope makes an angle with the horizontal. Using conservation of energy, find the maximum vertical height to which the ball will climb. Express your answer in terms of , , and . You may or may not use all of these quantities. v m 0 v v cos v sin v tan Kf = 0.5m(vcos( ))2 hmax = (vsin( ))2 2g v hmax v g ANSWER: Correct Interestingly, the answer does not depend on . The difference between this situation and the projectile case is that the ball moving up a slope has no kinetic energy at the top of its trajectory whereas the projectile launched at an angle does. Part I A ball is launched with initial speed from the ground level up a frictionless hill. The hill becomes steeper as the ball slides up; however, the ball remains in contact with the hill at all times. Using conservation of energy, find the maximum vertical height to which the ball will climb. Express your answer in terms of and . ANSWER: Correct The profile of the hill does not matter; the equation would have the same terms regardless of the steepness of the hill. Problem 10.14 A 12- -long spring is attached to the ceiling. When a 2.2 mass is hung from it, the spring stretches to a length of 17 . Part A What is the spring constant ? Express your answer to two significant figures and include the appropriate units. hmax = v2 2g v hmax v g hmax = v2 2g Ki + Ui = Kf + Uf cm kg cm k ANSWER: Correct Part B How long is the spring when a 3.0 mass is suspended from it? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Enhanced EOC: Problem 10.17 A 6.2 mass hanging from a spring scale is slowly lowered onto a vertical spring, as shown in . You may want to review ( pages 255 – 257) . For help with math skills, you may want to review: Solving Algebraic Equations = 430 k Nm kg y = 19 cm kg Part A What does the spring scale read just before the mass touches the lower spring? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces acting on the mass before it touches the scale. What is the net force on the mass? What is the force on the mass due to gravity? What is the force on the mass due to the scale? ANSWER: Correct Part B The scale reads 22 when the lower spring has been compressed by 2.7 . What is the value of the spring constant for the lower spring? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces acting on the mass. What is the net force on the mass? What is the force on the mass due to gravity? What is the force on the mass due to the scale? Use these to determine the force on the mass by the spring, taking note of the directions from your picture. How is the spring constant related to the force by the spring and the compression of the spring? Check your units. ANSWER: F = 61 N N cm k = 1400 k Nm Correct Part C At what compression length will the scale read zero? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Draw a picture showing the forces on the mass. When the scale reads zero, what is the force on the mass due to the scale? What is the gravitational force on the mass? What is the force on the mass by the spring? How is the compression length related to the force by the spring and the spring constant? Check your units. ANSWER: Correct Problem 10.18 Part A How far must you stretch a spring with = 800 to store 180 of energy? Express your answer to two significant figures and include the appropriate units. ANSWER: y = 4.2 cm k N/m J Correct Problem 10.22 A 15 runaway grocery cart runs into a spring with spring constant 230 and compresses it by 57 . Part A What was the speed of the cart just before it hit the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Spring Gun A spring-loaded toy gun is used to shoot a ball straight up in the air. The ball reaches a maximum height , measured from the equilibrium position of the spring. s = 0.67 m kg N/m cm v = 2.2 ms H Part A The same ball is shot straight up a second time from the same gun, but this time the spring is compressed only half as far before firing. How far up does the ball go this time? Neglect friction. Assume that the spring is ideal and that the distance by which the spring is compressed is negligible compared to . Hint 1. Potential energy of the spring The potential energy of a spring is proportional to the square of the distance the spring is compressed. The spring was compressed half the distance, so the mass, when launched, has one quarter of the energy as in the first trial. Hint 2. Potential energy of the ball At the highest point in the ball’s trajectory, all of the spring’s potential energy has been converted into gravitational potential energy of the ball. ANSWER: Correct A Bullet Is Fired into a Wooden Block A bullet of mass is fired horizontally with speed at a wooden block of mass resting on a frictionless table. The bullet hits the block and becomes completely embedded within it. After the bullet has come to rest within the block, the block, with the bullet in it, is traveling at speed . H height = H 4 mb vi mw vf Part A Which of the following best describes this collision? Hint 1. Types of collisions An inelastic collision is a collision in which kinetic energy is not conserved. In a partially inelastic collision, kinetic energy is lost, but the objects colliding do not stick together. From this information, you can infer what completely inelastic and elastic collisions are. ANSWER: Correct Part B Which of the following quantities, if any, are conserved during this collision? Hint 1. When is kinetic energy conserved? Kinetic energy is conserved only in perfectly elastic collisions. ANSWER: perfectly elastic partially inelastic perfectly inelastic Correct Part C What is the speed of the block/bullet system after the collision? Express your answer in terms of , , and . Hint 1. Find the momentum after the collision What is the total momentum of the block/bullet system after the collision? Express your answer in terms of and other given quantities. ANSWER: Hint 2. Use conservation of momentum The momentum of the block/bullet system is conserved. Therefore, the momentum before the collision is the same as the momentum after the collision. Find a second expression for , this time expressed as the total momentum of the system before the collision. Express your answer in terms of and other given quantities. ANSWER: kinetic energy only momentum only kinetic energy and momentum neither momentum nor kinetic energy vi mw mb ptotal vf ptotal = (mw + mb)vf ptotal vi ptotal = mbvi ANSWER: Correct Problem 10.31 Ball 1, with a mass of 150 and traveling at 15.0 , collides head on with ball 2, which has a mass of 340 and is initially at rest. Part A What are the final velocities of each ball if the collision is perfectly elastic? Express your answer with the appropriate units. ANSWER: Correct Part B Express your answer with the appropriate units. ANSWER: Correct Part C vf = mb vi mb+mw g m/s g (vfx) = -5.82 1 ms (vfx) = 9.18 2 ms What are the final velocities of each ball if the collision is perfectly inelastic? Express your answer with the appropriate units. ANSWER: Correct Part D Express your answer with the appropriate units. ANSWER: Correct Enhanced EOC: Problem 10.43 A package of mass is released from rest at a warehouse loading dock and slides down the = 2.2 – high, frictionless chute to a waiting truck. Unfortunately, the truck driver went on a break without having removed the previous package, of mass , from the bottom of the chute. You may want to review ( pages 265 – 269) . For help with math skills, you may want to review: Solving Algebraic Equations (vfx) = 4.59 1 ms (vfx) = 4.59 2 ms m h m 2m Part A Suppose the packages stick together. What is their common speed after the collision? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem There are two parts to this problem: the block sliding down the frictionless incline and the collision. What conservation laws are valid in each part? In terms of , what are the kinetic and potential energies of the block at the top of the incline? What is the potential energy of the same block at the bottom just before the collision? What are the kinetic energy and velocity of block just before the collision? What is conserved during the collision? What is the total momentum of the two blocks before the collision? What is the momentum of the two blocks stuck together after the collision? What is the velocity of the two blocks after the collision? ANSWER: Correct Part B Suppose the collision between the packages is perfectly elastic. To what height does the package of mass rebound? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem There are three parts to this problem: the block sliding down the incline, the collision, and mass going back up the incline. What conservation laws are valid in each part? m m v = 2.2 ms m m What is an elastic collision? For an elastic collision, how are the initial and final velocities related when one of the masses is initially at rest? Using the velocity of just before the collision from Part A, what is the velocity of just after the collision in this case? What are the kinetic and potential energies of mass just after the collision? What is the kinetic energy of mass at its maximum rebound height? Using conservation of energy, what is the potential energy of mass at its maximum height? What is the maximum height? ANSWER: Correct Problem 10.35 A cannon tilted up at a 35.0 angle fires a cannon ball at 79.0 from atop a 21.0 -high fortress wall. Part A What is the ball’s impact speed on the ground below? Express your answer with the appropriate units. ANSWER: Correct Problem 10.45 A 1000 safe is 2.5 above a heavy-duty spring when the rope holding the safe breaks. The safe hits the spring and compresses it 48 . m m m m m h = 24 cm $ m/s m vf = 81.6 ms kg m cm Part A What is the spring constant of the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 10.49 A 100 block on a frictionless table is firmly attached to one end of a spring with = 21 . The other end of the spring is anchored to the wall. A 30 ball is thrown horizontally toward the block with a speed of 6.0 . Part A If the collision is perfectly elastic, what is the ball’s speed immediately after the collision? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the maximum compression of the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: = 2.5×105 k Nm g k N/m g m/s v = 3.2 ms Correct Part C Repeat part A for the case of a perfectly inelastic collision. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D Repeat part B for the case of a perfectly inelastic collision. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 99.4%. You received 120.28 out of a possible total of 121 points. x = 0.19 m v = 1.4 ms x = 0.11 m

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Assignment 9 Due: 11:59pm on Friday, April 11, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Problem 11.2 Part A Evaluate the dot product if and . Express your answer using two significant figures. ANSWER: Correct Part B Evaluate the dot product if and . Express your answer using two significant figures. ANSWER: Correct Problem 11.4  A B = 5 − 6 A i ^ j ^ = −9 − 5 B i ^ j ^ A  B  = -15  A B = −5 + 9 A i ^ j ^ = 5 + 6 B i ^ j ^ A  B  = 29 Part A What is the angle between vectors and if and ? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part B What is the angle between vectors and if and ? Express your answer as an integer and include the appropriate units. ANSWER: Correct ± All Work and No Play Learning Goal: To be able to calculate work done by a constant force directed at different angles relative to displacement If an object undergoes displacement while being acted upon by a force (or several forces), it is said that work is being done on the object. If the object is moving in a straight line and the displacement and the force are known, the work done by the force can be calculated as , where is the work done by force on the object that undergoes displacement directed at angle relative to .  A B A = 2 + 5 ı ^  ^ B = −2 − 4 ı ^  ^  = 175  A B A = −6 + 2 ı ^  ^ B = − − 3 ı ^  ^  = 90 W =  = cos  F  s  F   s  W F  s  F  Note that depending on the value of , the work done can be positive, negative, or zero. In this problem, you will practice calculating work done on an object moving in a straight line. The first series of questions is related to the accompanying figure. Part A What can be said about the sign of the work done by the force ? ANSWER: Correct When , the cosine of is zero, and therefore the work done is zero. Part B cos  F  1 It is positive. It is negative. It is zero. There is not enough information to answer the question.  = 90  What can be said about the work done by force ? ANSWER: Correct When , is positive, and so the work done is positive. Part C The work done by force is ANSWER: Correct When , is negative, and so the work done is negative. Part D The work done by force is ANSWER: F  2 It is positive. It is negative. It is zero. 0 <  < 90 cos  F  3 positive negative zero 90 <  < 180 cos  F  4 Correct Part E The work done by force is ANSWER: Correct positive negative zero F  5 positive negative zero Part F The work done by force is ANSWER: Correct Part G The work done by force is ANSWER: Correct In the next series of questions, you will use the formula to calculate the work done by various forces on an object that moves 160 meters to the right. F  6 positive negative zero F  7 positive negative zero W =  = cos  F  s  F   s  Part H Find the work done by the 18-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Part I Find the work done by the 30-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Part J Find the work done by the 12-newton force. Use two significant figures in your answer. Express your answer in joules. W W = 2900 J W W = 4200 J W ANSWER: Correct Part K Find the work done by the 15-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Introduction to Potential Energy Learning Goal: Understand that conservative forces can be removed from the work integral by incorporating them into a new form of energy called potential energy that must be added to the kinetic energy to get the total mechanical energy. The first part of this problem contains short-answer questions that review the work-energy theorem. In the second part we introduce the concept of potential energy. But for now, please answer in terms of the work-energy theorem. Work-Energy Theorem The work-energy theorem states , where is the work done by all forces that act on the object, and and are the initial and final kinetic energies, respectively. Part A The work-energy theorem states that a force acting on a particle as it moves over a ______ changes the ______ energy of the particle if the force has a component parallel to the motion. W = -1900 J W W = -1800 J Kf = Ki + Wall Wall Ki Kf Choose the best answer to fill in the blanks above: ANSWER: Correct It is important that the force have a component acting in the direction of motion. For example, if a ball is attached to a string and whirled in uniform circular motion, the string does apply a force to the ball, but since the string's force is always perpendicular to the motion it does no work and cannot change the kinetic energy of the ball. Part B To calculate the change in energy, you must know the force as a function of _______. The work done by the force causes the energy change. Choose the best answer to fill in the blank above: ANSWER: Correct Part C To illustrate the work-energy concept, consider the case of a stone falling from to under the influence of gravity. Using the work-energy concept, we say that work is done by the gravitational _____, resulting in an increase of the ______ energy of the stone. Choose the best answer to fill in the blanks above: distance / potential distance / kinetic vertical displacement / potential none of the above acceleration work distance potential energy xi xf ANSWER: Correct Potential Energy You should read about potential energy in your text before answering the following questions. Potential energy is a concept that builds on the work-energy theorem, enlarging the concept of energy in the most physically useful way. The key aspect that allows for potential energy is the existence of conservative forces, forces for which the work done on an object does not depend on the path of the object, only the initial and final positions of the object. The gravitational force is conservative; the frictional force is not. The change in potential energy is the negative of the work done by conservative forces. Hence considering the initial and final potential energies is equivalent to calculating the work done by the conservative forces. When potential energy is used, it replaces the work done by the associated conservative force. Then only the work due to nonconservative forces needs to be calculated. In summary, when using the concept of potential energy, only nonconservative forces contribute to the work, which now changes the total energy: , where and are the final and initial potential energies, and is the work due only to nonconservative forces. Now, we will revisit the falling stone example using the concept of potential energy. Part D Rather than ascribing the increased kinetic energy of the stone to the work of gravity, we now (when using potential energy rather than work-energy) say that the increased kinetic energy comes from the ______ of the _______ energy. Choose the best answer to fill in the blanks above: ANSWER: force / kinetic potential energy / potential force / potential potential energy / kinetic Kf + Uf = Ef = Wnc + Ei = Wnc + Ki + Ui Uf Ui Wnc Correct Part E This process happens in such a way that total mechanical energy, equal to the ______ of the kinetic and potential energies, is _______. Choose the best answer to fill in the blanks above: ANSWER: Correct Problem 11.7 Part A How much work is done by the force 2.2 6.6 on a particle that moves through displacement 3.9 Express your answer to two significant figures and include the appropriate units. ANSWER: work / potential force / kinetic change / potential sum / conserved sum / zero sum / not conserved difference / conserved F  = (− + i ^ ) N j ^ ! = r m i ^ Correct Part B How much work is done by the force 2.2 6.6 on a particle that moves through displacement 3.9 Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.10 A 1.8 book is lying on a 0.80- -high table. You pick it up and place it on a bookshelf 2.27 above the floor. Part A How much work does gravity do on the book? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B W = -8.6 J F  = (− + i ^ ) N j ^ ! = r m? j ^ W = 26 J kg m m Wg = -26 J How much work does your hand do on the book? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.12 The three ropes shown in the bird's-eye view of the figure are used to drag a crate 3.3 across the floor. Part A How much work is done by each of the three forces? Express your answers using two significant figures. Enter your answers numerically separated by commas. ANSWER: WH = 26 J m W1 , W2 , W3 = 1.9,1.2,-2.1 kJ Correct Enhanced EOC: Problem 11.16 A 1.2 particle moving along the x-axis experiences the force shown in the figure. The particle's velocity is 4.6 at . You may want to review ( pages 286 - 287) . For help with math skills, you may want to review: The Definite Integral Part A What is its velocity at ? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the work–kinetic energy theorem? What is the kinetic energy at ? How is the work done in going from to related to force shown in the graph? Using the work–kinetic energy theorem, what is the kinetic energy at ? What is the velocity at ? ANSWER: kg m/s x = 0m x = 2m x = 0 m x = 0 m x = 2 m x = 2 m x = 2 m Correct Part B What is its velocity at ? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the work–kinetic energy theorem? What is the kinetic energy at ? How is the work done in going from to related to force shown in the graph? Can the work be negative? Using the work–kinetic energy theorem, what is the kinetic energy at ? What is the velocity at ? ANSWER: Correct Work on a Sliding Block A block of weight sits on a frictionless inclined plane, which makes an angle with respect to the horizontal, as shown. A force of magnitude , applied parallel to the incline, pulls the block up the plane at constant speed. v = 6.2 ms x = 4m x = 0 m x = 0 m x = 4 m x = 4 m x = 4 m v = 4.6 ms w  F Part A The block moves a distance up the incline. The block does not stop after moving this distance but continues to move with constant speed. What is the total work done on the block by all forces? (Include only the work done after the block has started moving, not the work needed to start the block moving from rest.) Express your answer in terms of given quantities. Hint 1. What physical principle to use To find the total work done on the block, use the work-energy theorem: . Hint 2. Find the change in kinetic energy What is the change in the kinetic energy of the block, from the moment it starts moving until it has been pulled a distance ? Remember that the block is pulled at constant speed. Hint 1. Consider kinetic energy If the block's speed does not change, its kinetic energy cannot change. ANSWER: ANSWER: L Wtot Wtot = Kf − Ki L Kf − Ki = 0 Wtot = 0 Correct Part B What is , the work done on the block by the force of gravity as the block moves a distance up the incline? Express the work done by gravity in terms of the weight and any other quantities given in the problem introduction. Hint 1. Force diagram Hint 2. Force of gravity component What is the component of the force of gravity in the direction of the block's displacement (along the inclined plane)? Express your answer in terms of and . Hint 1. Relative direction of the force and the motion Remember that the force of gravity acts down the plane, whereas the block's displacement is directed up the plane. ANSWER: Wg L w w  ANSWER: Correct Part C What is , the work done on the block by the applied force as the block moves a distance up the incline? Express your answer in terms of and other given quantities. Hint 1. How to find the work done by a constant force Remember that the work done on an object by a particular force is the integral of the dot product of the force and the instantaneous displacement of the object, over the path followed by the object. In this case, since the force is constant and the path is a straight segment of length up the inclined plane, the dot product becomes simple multiplication. ANSWER: Correct Part D What is , the work done on the block by the normal force as the block moves a distance up the inclined plane? Express your answer in terms of given quantities. Hint 1. First step in computing the work Fg|| = −wsin() Wg = −wLsin() WF F L F L WF = FL Wnormal L The work done by the normal force is equal to the dot product of the force vector and the block's displacement vector. The normal force and the block's displacement vector are perpendicular. Therefore, what is their dot product? ANSWER: ANSWER: Correct Problem 11.20 A particle moving along the -axis has the potential energy , where is in . Part A What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. N  L = 0 Wnormal = 0 y U = 3.2y3 J y m y y = 0 m Fy = 0 N y y = 1 m ANSWER: Correct Part C What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.28 A cable with 25.0 of tension pulls straight up on a 1.08 block that is initially at rest. Part A What is the block's speed after being lifted 2.40 ? Solve this problem using work and energy. Express your answer with the appropriate units. ANSWER: Correct Fy = -9.6 N y y = 2 m Fy = -38 N N kg m vf = 8.00 ms Problem 11.29 Part A How much work does an elevator motor do to lift a 1500 elevator a height of 110 ? Express your answer with the appropriate units. ANSWER: Correct Part B How much power must the motor supply to do this in 50 at constant speed? Express your answer with the appropriate units. ANSWER: Correct Problem 11.32 How many energy is consumed by a 1.20 hair dryer used for 10.0 and a 11.0 night light left on for 16.0 ? Part A Hair dryer: Express your answer with the appropriate units. kg m Wext = 1.62×106 J s = 3.23×104 P W kW min W hr ANSWER: Correct Part B Night light: Express your answer with the appropriate units. ANSWER: Correct Problem 11.42 A 2500 elevator accelerates upward at 1.20 for 10.0 , starting from rest. Part A How much work does gravity do on the elevator? Express your answer with the appropriate units. ANSWER: Correct W = 7.20×105 J = 6.34×105 W J kg m/s2 m −2.45×105 J Part B How much work does the tension in the elevator cable do on the elevator? Express your answer with the appropriate units. ANSWER: Correct Part C Use the work-kinetic energy theorem to find the kinetic energy of the elevator as it reaches 10.0 . Express your answer with the appropriate units. ANSWER: Correct Part D What is the speed of the elevator as it reaches 10.0 ? Express your answer with the appropriate units. ANSWER: Correct 2.75×105 J m 3.00×104 J m 4.90 ms Problem 11.47 A horizontal spring with spring constant 130 is compressed 17 and used to launch a 2.4 box across a frictionless, horizontal surface. After the box travels some distance, the surface becomes rough. The coefficient of kinetic friction of the box on the surface is 0.15. Part A Use work and energy to find how far the box slides across the rough surface before stopping. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.49 Truck brakes can fail if they get too hot. In some mountainous areas, ramps of loose gravel are constructed to stop runaway trucks that have lost their brakes. The combination of a slight upward slope and a large coefficient of rolling friction as the truck tires sink into the gravel brings the truck safely to a halt. Suppose a gravel ramp slopes upward at 6.0 and the coefficient of rolling friction is 0.45. Part A Use work and energy to find the length of a ramp that will stop a 15,000 truck that enters the ramp at 30 . Express your answer to two significant figures and include the appropriate units. ANSWER: Correct N/m cm kg l = 53 cm kg m/s l = 83 m Problem 11.51 Use work and energy to find an expression for the speed of the block in the following figure just before it hits the floor. Part A Find an expression for the speed of the block if the coefficient of kinetic friction for the block on the table is . Express your answer in terms of the variables , , , , and free fall acceleration . ANSWER: Part B Find an expression for the speed of the block if the table is frictionless. Express your answer in terms of the variables , , , and free fall acceleration . ANSWER: μk M m h μk g v = M m h g Problem 11.57 The spring shown in the figure is compressed 60 and used to launch a 100 physics student. The track is frictionless until it starts up the incline. The student's coefficient of kinetic friction on the incline is 0.12 . Part A What is the student's speed just after losing contact with the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B How far up the incline does the student go? Express your answer to two significant figures and include the appropriate units. ANSWER: v = cm kg 30 v = 17 ms Correct Score Summary: Your score on this assignment is 93.6%. You received 112.37 out of a possible total of 120 points. !s = 41 m

Assignment 9 Due: 11:59pm on Friday, April 11, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Problem 11.2 Part A Evaluate the dot product if and . Express your answer using two significant figures. ANSWER: Correct Part B Evaluate the dot product if and . Express your answer using two significant figures. ANSWER: Correct Problem 11.4  A B = 5 − 6 A i ^ j ^ = −9 − 5 B i ^ j ^ A  B  = -15  A B = −5 + 9 A i ^ j ^ = 5 + 6 B i ^ j ^ A  B  = 29 Part A What is the angle between vectors and if and ? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part B What is the angle between vectors and if and ? Express your answer as an integer and include the appropriate units. ANSWER: Correct ± All Work and No Play Learning Goal: To be able to calculate work done by a constant force directed at different angles relative to displacement If an object undergoes displacement while being acted upon by a force (or several forces), it is said that work is being done on the object. If the object is moving in a straight line and the displacement and the force are known, the work done by the force can be calculated as , where is the work done by force on the object that undergoes displacement directed at angle relative to .  A B A = 2 + 5 ı ^  ^ B = −2 − 4 ı ^  ^  = 175  A B A = −6 + 2 ı ^  ^ B = − − 3 ı ^  ^  = 90 W =  = cos  F  s  F   s  W F  s  F  Note that depending on the value of , the work done can be positive, negative, or zero. In this problem, you will practice calculating work done on an object moving in a straight line. The first series of questions is related to the accompanying figure. Part A What can be said about the sign of the work done by the force ? ANSWER: Correct When , the cosine of is zero, and therefore the work done is zero. Part B cos  F  1 It is positive. It is negative. It is zero. There is not enough information to answer the question.  = 90  What can be said about the work done by force ? ANSWER: Correct When , is positive, and so the work done is positive. Part C The work done by force is ANSWER: Correct When , is negative, and so the work done is negative. Part D The work done by force is ANSWER: F  2 It is positive. It is negative. It is zero. 0 <  < 90 cos  F  3 positive negative zero 90 <  < 180 cos  F  4 Correct Part E The work done by force is ANSWER: Correct positive negative zero F  5 positive negative zero Part F The work done by force is ANSWER: Correct Part G The work done by force is ANSWER: Correct In the next series of questions, you will use the formula to calculate the work done by various forces on an object that moves 160 meters to the right. F  6 positive negative zero F  7 positive negative zero W =  = cos  F  s  F   s  Part H Find the work done by the 18-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Part I Find the work done by the 30-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Part J Find the work done by the 12-newton force. Use two significant figures in your answer. Express your answer in joules. W W = 2900 J W W = 4200 J W ANSWER: Correct Part K Find the work done by the 15-newton force. Use two significant figures in your answer. Express your answer in joules. ANSWER: Correct Introduction to Potential Energy Learning Goal: Understand that conservative forces can be removed from the work integral by incorporating them into a new form of energy called potential energy that must be added to the kinetic energy to get the total mechanical energy. The first part of this problem contains short-answer questions that review the work-energy theorem. In the second part we introduce the concept of potential energy. But for now, please answer in terms of the work-energy theorem. Work-Energy Theorem The work-energy theorem states , where is the work done by all forces that act on the object, and and are the initial and final kinetic energies, respectively. Part A The work-energy theorem states that a force acting on a particle as it moves over a ______ changes the ______ energy of the particle if the force has a component parallel to the motion. W = -1900 J W W = -1800 J Kf = Ki + Wall Wall Ki Kf Choose the best answer to fill in the blanks above: ANSWER: Correct It is important that the force have a component acting in the direction of motion. For example, if a ball is attached to a string and whirled in uniform circular motion, the string does apply a force to the ball, but since the string's force is always perpendicular to the motion it does no work and cannot change the kinetic energy of the ball. Part B To calculate the change in energy, you must know the force as a function of _______. The work done by the force causes the energy change. Choose the best answer to fill in the blank above: ANSWER: Correct Part C To illustrate the work-energy concept, consider the case of a stone falling from to under the influence of gravity. Using the work-energy concept, we say that work is done by the gravitational _____, resulting in an increase of the ______ energy of the stone. Choose the best answer to fill in the blanks above: distance / potential distance / kinetic vertical displacement / potential none of the above acceleration work distance potential energy xi xf ANSWER: Correct Potential Energy You should read about potential energy in your text before answering the following questions. Potential energy is a concept that builds on the work-energy theorem, enlarging the concept of energy in the most physically useful way. The key aspect that allows for potential energy is the existence of conservative forces, forces for which the work done on an object does not depend on the path of the object, only the initial and final positions of the object. The gravitational force is conservative; the frictional force is not. The change in potential energy is the negative of the work done by conservative forces. Hence considering the initial and final potential energies is equivalent to calculating the work done by the conservative forces. When potential energy is used, it replaces the work done by the associated conservative force. Then only the work due to nonconservative forces needs to be calculated. In summary, when using the concept of potential energy, only nonconservative forces contribute to the work, which now changes the total energy: , where and are the final and initial potential energies, and is the work due only to nonconservative forces. Now, we will revisit the falling stone example using the concept of potential energy. Part D Rather than ascribing the increased kinetic energy of the stone to the work of gravity, we now (when using potential energy rather than work-energy) say that the increased kinetic energy comes from the ______ of the _______ energy. Choose the best answer to fill in the blanks above: ANSWER: force / kinetic potential energy / potential force / potential potential energy / kinetic Kf + Uf = Ef = Wnc + Ei = Wnc + Ki + Ui Uf Ui Wnc Correct Part E This process happens in such a way that total mechanical energy, equal to the ______ of the kinetic and potential energies, is _______. Choose the best answer to fill in the blanks above: ANSWER: Correct Problem 11.7 Part A How much work is done by the force 2.2 6.6 on a particle that moves through displacement 3.9 Express your answer to two significant figures and include the appropriate units. ANSWER: work / potential force / kinetic change / potential sum / conserved sum / zero sum / not conserved difference / conserved F  = (− + i ^ ) N j ^ ! = r m i ^ Correct Part B How much work is done by the force 2.2 6.6 on a particle that moves through displacement 3.9 Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.10 A 1.8 book is lying on a 0.80- -high table. You pick it up and place it on a bookshelf 2.27 above the floor. Part A How much work does gravity do on the book? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B W = -8.6 J F  = (− + i ^ ) N j ^ ! = r m? j ^ W = 26 J kg m m Wg = -26 J How much work does your hand do on the book? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.12 The three ropes shown in the bird's-eye view of the figure are used to drag a crate 3.3 across the floor. Part A How much work is done by each of the three forces? Express your answers using two significant figures. Enter your answers numerically separated by commas. ANSWER: WH = 26 J m W1 , W2 , W3 = 1.9,1.2,-2.1 kJ Correct Enhanced EOC: Problem 11.16 A 1.2 particle moving along the x-axis experiences the force shown in the figure. The particle's velocity is 4.6 at . You may want to review ( pages 286 - 287) . For help with math skills, you may want to review: The Definite Integral Part A What is its velocity at ? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the work–kinetic energy theorem? What is the kinetic energy at ? How is the work done in going from to related to force shown in the graph? Using the work–kinetic energy theorem, what is the kinetic energy at ? What is the velocity at ? ANSWER: kg m/s x = 0m x = 2m x = 0 m x = 0 m x = 2 m x = 2 m x = 2 m Correct Part B What is its velocity at ? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the work–kinetic energy theorem? What is the kinetic energy at ? How is the work done in going from to related to force shown in the graph? Can the work be negative? Using the work–kinetic energy theorem, what is the kinetic energy at ? What is the velocity at ? ANSWER: Correct Work on a Sliding Block A block of weight sits on a frictionless inclined plane, which makes an angle with respect to the horizontal, as shown. A force of magnitude , applied parallel to the incline, pulls the block up the plane at constant speed. v = 6.2 ms x = 4m x = 0 m x = 0 m x = 4 m x = 4 m x = 4 m v = 4.6 ms w  F Part A The block moves a distance up the incline. The block does not stop after moving this distance but continues to move with constant speed. What is the total work done on the block by all forces? (Include only the work done after the block has started moving, not the work needed to start the block moving from rest.) Express your answer in terms of given quantities. Hint 1. What physical principle to use To find the total work done on the block, use the work-energy theorem: . Hint 2. Find the change in kinetic energy What is the change in the kinetic energy of the block, from the moment it starts moving until it has been pulled a distance ? Remember that the block is pulled at constant speed. Hint 1. Consider kinetic energy If the block's speed does not change, its kinetic energy cannot change. ANSWER: ANSWER: L Wtot Wtot = Kf − Ki L Kf − Ki = 0 Wtot = 0 Correct Part B What is , the work done on the block by the force of gravity as the block moves a distance up the incline? Express the work done by gravity in terms of the weight and any other quantities given in the problem introduction. Hint 1. Force diagram Hint 2. Force of gravity component What is the component of the force of gravity in the direction of the block's displacement (along the inclined plane)? Express your answer in terms of and . Hint 1. Relative direction of the force and the motion Remember that the force of gravity acts down the plane, whereas the block's displacement is directed up the plane. ANSWER: Wg L w w  ANSWER: Correct Part C What is , the work done on the block by the applied force as the block moves a distance up the incline? Express your answer in terms of and other given quantities. Hint 1. How to find the work done by a constant force Remember that the work done on an object by a particular force is the integral of the dot product of the force and the instantaneous displacement of the object, over the path followed by the object. In this case, since the force is constant and the path is a straight segment of length up the inclined plane, the dot product becomes simple multiplication. ANSWER: Correct Part D What is , the work done on the block by the normal force as the block moves a distance up the inclined plane? Express your answer in terms of given quantities. Hint 1. First step in computing the work Fg|| = −wsin() Wg = −wLsin() WF F L F L WF = FL Wnormal L The work done by the normal force is equal to the dot product of the force vector and the block's displacement vector. The normal force and the block's displacement vector are perpendicular. Therefore, what is their dot product? ANSWER: ANSWER: Correct Problem 11.20 A particle moving along the -axis has the potential energy , where is in . Part A What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. N  L = 0 Wnormal = 0 y U = 3.2y3 J y m y y = 0 m Fy = 0 N y y = 1 m ANSWER: Correct Part C What is the -component of the force on the particle at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.28 A cable with 25.0 of tension pulls straight up on a 1.08 block that is initially at rest. Part A What is the block's speed after being lifted 2.40 ? Solve this problem using work and energy. Express your answer with the appropriate units. ANSWER: Correct Fy = -9.6 N y y = 2 m Fy = -38 N N kg m vf = 8.00 ms Problem 11.29 Part A How much work does an elevator motor do to lift a 1500 elevator a height of 110 ? Express your answer with the appropriate units. ANSWER: Correct Part B How much power must the motor supply to do this in 50 at constant speed? Express your answer with the appropriate units. ANSWER: Correct Problem 11.32 How many energy is consumed by a 1.20 hair dryer used for 10.0 and a 11.0 night light left on for 16.0 ? Part A Hair dryer: Express your answer with the appropriate units. kg m Wext = 1.62×106 J s = 3.23×104 P W kW min W hr ANSWER: Correct Part B Night light: Express your answer with the appropriate units. ANSWER: Correct Problem 11.42 A 2500 elevator accelerates upward at 1.20 for 10.0 , starting from rest. Part A How much work does gravity do on the elevator? Express your answer with the appropriate units. ANSWER: Correct W = 7.20×105 J = 6.34×105 W J kg m/s2 m −2.45×105 J Part B How much work does the tension in the elevator cable do on the elevator? Express your answer with the appropriate units. ANSWER: Correct Part C Use the work-kinetic energy theorem to find the kinetic energy of the elevator as it reaches 10.0 . Express your answer with the appropriate units. ANSWER: Correct Part D What is the speed of the elevator as it reaches 10.0 ? Express your answer with the appropriate units. ANSWER: Correct 2.75×105 J m 3.00×104 J m 4.90 ms Problem 11.47 A horizontal spring with spring constant 130 is compressed 17 and used to launch a 2.4 box across a frictionless, horizontal surface. After the box travels some distance, the surface becomes rough. The coefficient of kinetic friction of the box on the surface is 0.15. Part A Use work and energy to find how far the box slides across the rough surface before stopping. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 11.49 Truck brakes can fail if they get too hot. In some mountainous areas, ramps of loose gravel are constructed to stop runaway trucks that have lost their brakes. The combination of a slight upward slope and a large coefficient of rolling friction as the truck tires sink into the gravel brings the truck safely to a halt. Suppose a gravel ramp slopes upward at 6.0 and the coefficient of rolling friction is 0.45. Part A Use work and energy to find the length of a ramp that will stop a 15,000 truck that enters the ramp at 30 . Express your answer to two significant figures and include the appropriate units. ANSWER: Correct N/m cm kg l = 53 cm kg m/s l = 83 m Problem 11.51 Use work and energy to find an expression for the speed of the block in the following figure just before it hits the floor. Part A Find an expression for the speed of the block if the coefficient of kinetic friction for the block on the table is . Express your answer in terms of the variables , , , , and free fall acceleration . ANSWER: Part B Find an expression for the speed of the block if the table is frictionless. Express your answer in terms of the variables , , , and free fall acceleration . ANSWER: μk M m h μk g v = M m h g Problem 11.57 The spring shown in the figure is compressed 60 and used to launch a 100 physics student. The track is frictionless until it starts up the incline. The student's coefficient of kinetic friction on the incline is 0.12 . Part A What is the student's speed just after losing contact with the spring? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B How far up the incline does the student go? Express your answer to two significant figures and include the appropriate units. ANSWER: v = cm kg 30 v = 17 ms Correct Score Summary: Your score on this assignment is 93.6%. You received 112.37 out of a possible total of 120 points. !s = 41 m

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Sex, Gender, and Popular Culture Spring 2015 Look through popular magazines, and see if you can find advertisements that objectify women in order to sell a product. Alternately, you may use an advertisement on television (but make sure to provide a link to the ad so I can see it!). Study these images then write a paper about objectification that deals with all or some of the following: • What effect(s), if any, do you think the objectification of women’s bodies has on our culture? • Jean Kilbourne states “turning a human being into a thing is almost always the first step toward justifying violence against that person.” What do you think she means by this? Do you agree with her reasoning? Why or why not? • Some people would argue that depicting a woman’s body as an object is a form of art. What is your opinion of this point of view? Explain your reasoning. • Why do you think that women are objectified more often than men are? • How does sexualization and objectification play out differently across racial lines? • Kilbourne explains that the consequences of being objectified are different – and more serious – for women than for men. Do you agree? How is the world different for women than it is for men? How do objectified images of women interact with those in our culture differently from the way images of men do? Why is it important to look at images in the context of the culture? • What is the difference between sexual objectification and sexual subjectification? (Ros Gill ) • How do ads construct violent white masculinity and how does that vision of masculinity hurt both men and women? Throughout your written analysis, be sure to make clear and specific reference to the images you selected, and please submit these images with your paper. Make sure you engage with and reference to at least 4 of the following authors: Kilbourne, Bordo, Hunter & Soto, Rose, Durham, Gill, Katz, Schuchardt, Ono and Buescher. Guidelines:  Keep your content focused on structural, systemic, institutional factors rather than the individual: BE ANALYTICAL NOT ANECDOTAL.  Avoid using the first person or including personal stories/reactions. You must make sure to actively engage with your readings: these essays need to be informed and framed by the theoretical material you have been reading this semester.  Keep within the 4-6 page limit; use 12-point font, double spacing and 1-inch margins.  Use formal writing conventions (introduction/thesis statement, body, conclusion) and correct grammar. Resources may be cited within the text of your paper, i.e. (Walters, 2013).

Sex, Gender, and Popular Culture Spring 2015 Look through popular magazines, and see if you can find advertisements that objectify women in order to sell a product. Alternately, you may use an advertisement on television (but make sure to provide a link to the ad so I can see it!). Study these images then write a paper about objectification that deals with all or some of the following: • What effect(s), if any, do you think the objectification of women’s bodies has on our culture? • Jean Kilbourne states “turning a human being into a thing is almost always the first step toward justifying violence against that person.” What do you think she means by this? Do you agree with her reasoning? Why or why not? • Some people would argue that depicting a woman’s body as an object is a form of art. What is your opinion of this point of view? Explain your reasoning. • Why do you think that women are objectified more often than men are? • How does sexualization and objectification play out differently across racial lines? • Kilbourne explains that the consequences of being objectified are different – and more serious – for women than for men. Do you agree? How is the world different for women than it is for men? How do objectified images of women interact with those in our culture differently from the way images of men do? Why is it important to look at images in the context of the culture? • What is the difference between sexual objectification and sexual subjectification? (Ros Gill ) • How do ads construct violent white masculinity and how does that vision of masculinity hurt both men and women? Throughout your written analysis, be sure to make clear and specific reference to the images you selected, and please submit these images with your paper. Make sure you engage with and reference to at least 4 of the following authors: Kilbourne, Bordo, Hunter & Soto, Rose, Durham, Gill, Katz, Schuchardt, Ono and Buescher. Guidelines:  Keep your content focused on structural, systemic, institutional factors rather than the individual: BE ANALYTICAL NOT ANECDOTAL.  Avoid using the first person or including personal stories/reactions. You must make sure to actively engage with your readings: these essays need to be informed and framed by the theoretical material you have been reading this semester.  Keep within the 4-6 page limit; use 12-point font, double spacing and 1-inch margins.  Use formal writing conventions (introduction/thesis statement, body, conclusion) and correct grammar. Resources may be cited within the text of your paper, i.e. (Walters, 2013).

The objectification of women has been a very controversial topic … Read More...
Chapter 06 Reading Questions Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Chapter 6 Reading Quiz Question 17 Part A Which of the following represents an example of intraspecific exploitation competition? ANSWER: Chapter 6 Reading Quiz Question 3 Part A A species’s realized niche _____. ANSWER: Chapter 6 Reading Quiz Question 2 Part A Two species of ant compete for limited resources in a front yard, until only one species is able to remain. This is an example of _____. ANSWER: Hungry and fighting for a meal, a jackal quickly consumes the carcass of a young antelope while fighting off the feeding efforts of a vulture. Two species of worker ants converge on pieces of a donut left behind from the people in the park. The leaves of the huge hickory tree overshadow the young hickory tree saplings struggling for light just below. Spotting a fresh source of grasses, the large male bison moves over to graze, pushing the smaller bison out of the way. is smaller than the fundamental niche because of the constraints of competition is broader than a species’s fundamental niche does not overlap with similar species includes environmental conditions that are not included in the fundamental niche Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 20 Part A In which of the following situations would we expect a parasite to spread the fastest? ANSWER: Chapter 6 Reading Quiz Question 6 Part A Many plants have evolved adaptations to discourage herbivore feeding. Which one of the following is an example of such coevolution between bison and prairie plants? ANSWER: Chapter 6 Reading Quiz Question 5 Part A When predators selectively prey on the old and sick members of a prey population, they _____. ANSWER: mutualism intraspecific competition the competitive exclusion principle niche differentiation concentrated hosts with slowly moving vectors widely dispersed hosts with rapidly moving vectors concentrated hosts with rapidly moving vectors widely dispersed hosts with slow-moving vectors the ability to regrow after a wildfire thorns the production of nutritious fruits longer and thicker roots Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 21 Part A Cattle egrets are large white birds that follow grazing cattle. The cattle disturb the grass and stir up insects upon which the egrets feed. The cattle do not seem to mind the birds and gain nothing from this relationship. This relationship between cattle and cattle egrets is a type of _____. ANSWER: Chapter 6 Reading Quiz Question 8 Part A Which of the following is a mutualistic relationship that has a significant effect on an entire ecological community? ANSWER: Chapter 6 Reading Quiz Question 7 Part A Which one of the following relationships would be considered a win/win? ANSWER: cause the overall health of the prey population to increase illustrate the process of prey switching increase the likelihood of parasitic infections of the prey cause the overall health of the prey population to decrease parasitism commensalism mimicry mutualism Polar bears are the top predator influencing the abundance of seals and sea lions in a region. Hermit crabs inhabit the abandoned shells of marine snails that died long ago. Fungus-plant root associations benefit most of the plants living in a prairie. Mosquitoes function as a vector in the widespread transmission of malaria to people living in Ecuador. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 23 Part A In examining a terrestrial food web, we expect that the _____. ANSWER: Chapter 6 Reading Quiz Question 22 Part A Energy is lost as it moves from one trophic level to the next because _____. ANSWER: Chapter 6 Reading Quiz Question 11 Part A The research on the reintroduction of wolves into Yellowstone National Park reveals that in this ecosystem, wolves represent _____. ANSWER: mutualism predation parasitism commensalism biomass of primary consumers exceeds the biomass of producers number of secondary consumers exceeds the number of producers biomass of primary consumers exceeds the biomass of secondary consumers number of tertiary consumers exceeds the number of secondary consumers one trophic level does not consume the entire trophic level below it some of the calories consumed drive cellular activities and do not add mass some ingested materials are undigested and eliminated All of the listed responses are correct. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 10 Part A Overhunting of deer followed by a very difficult winter caused the deer population on an island to drop by 80%. In the next two years, visitors to the island were surprised to see many young trees sprouting up at the edges of the forest. This change in the number of saplings as a result of the decline of the deer population represents _____. ANSWER: Chapter 6 Reading Quiz Question 24 Part A The May 18, 1980, eruption of Mount Saint Helens blasted away soil and produced massive mudflows that scoured the adjacent region down to bare rock. Pumice rock that covered the area is eroding down to smaller gravel. This situation represents _____. ANSWER: Chapter 6 Reading Quiz Question 15 Part A In some ecosystems, succession increases the chance of disturbance. In these ecosystems, _____. a keystone producer a keystone herbivore a vital primary consumer a keystone predator a trophic cascade a decline in trophic level efficiency the emergence of a new ecological community a loss of a trophic level from a food web primary succession with the removal of all ecological legacies secondary succession with the removal of all ecological legacies secondary succession with several ecological legacies primary succession with several ecological legacies Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 7 5/21/2014 8:01 PM ANSWER: Chapter 6 Reading Quiz Question 12 Part A A forest is logged, leaving behind the seeds and saplings of many shrubs and trees. These seeds and saplings represent _____. ANSWER: Chapter 6 Reading Quiz Question 13 Part A During primary succession, populations of different species replace one another over time because of _____. ANSWER: Chapter 6 Reading Quiz Question 14 Part A Which one of the following represents a climax community in southern Alaska? ANSWER: ecosystems begin again with primary succession climax communities are expected climax communities may not occur disturbances usually result in virtually no ecological legacy ecological legacies a climax community primary succession pioneer species migration facilitation competition All of the listed responses are correct. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 9 Part A In general, _____. ANSWER: Score Summary: Your score on this assignment is 0.0%. You received 0 out of a possible total of 19 points. the group of species associated with a white spruce forest lichens and mosses that colonize exposed rock birch and alder trees herbs and a few low shrubs that replace lichens and mosses food webs usually have 8-10 trophic levels food webs are interconnected food chains food chains consist of many interrelated food webs food webs consist of either consumers or producers Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 7 5/21/2014 8:01 PM

Chapter 06 Reading Questions Due: 11:59pm on Friday, May 23, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Chapter 6 Reading Quiz Question 17 Part A Which of the following represents an example of intraspecific exploitation competition? ANSWER: Chapter 6 Reading Quiz Question 3 Part A A species’s realized niche _____. ANSWER: Chapter 6 Reading Quiz Question 2 Part A Two species of ant compete for limited resources in a front yard, until only one species is able to remain. This is an example of _____. ANSWER: Hungry and fighting for a meal, a jackal quickly consumes the carcass of a young antelope while fighting off the feeding efforts of a vulture. Two species of worker ants converge on pieces of a donut left behind from the people in the park. The leaves of the huge hickory tree overshadow the young hickory tree saplings struggling for light just below. Spotting a fresh source of grasses, the large male bison moves over to graze, pushing the smaller bison out of the way. is smaller than the fundamental niche because of the constraints of competition is broader than a species’s fundamental niche does not overlap with similar species includes environmental conditions that are not included in the fundamental niche Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 1 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 20 Part A In which of the following situations would we expect a parasite to spread the fastest? ANSWER: Chapter 6 Reading Quiz Question 6 Part A Many plants have evolved adaptations to discourage herbivore feeding. Which one of the following is an example of such coevolution between bison and prairie plants? ANSWER: Chapter 6 Reading Quiz Question 5 Part A When predators selectively prey on the old and sick members of a prey population, they _____. ANSWER: mutualism intraspecific competition the competitive exclusion principle niche differentiation concentrated hosts with slowly moving vectors widely dispersed hosts with rapidly moving vectors concentrated hosts with rapidly moving vectors widely dispersed hosts with slow-moving vectors the ability to regrow after a wildfire thorns the production of nutritious fruits longer and thicker roots Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 2 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 21 Part A Cattle egrets are large white birds that follow grazing cattle. The cattle disturb the grass and stir up insects upon which the egrets feed. The cattle do not seem to mind the birds and gain nothing from this relationship. This relationship between cattle and cattle egrets is a type of _____. ANSWER: Chapter 6 Reading Quiz Question 8 Part A Which of the following is a mutualistic relationship that has a significant effect on an entire ecological community? ANSWER: Chapter 6 Reading Quiz Question 7 Part A Which one of the following relationships would be considered a win/win? ANSWER: cause the overall health of the prey population to increase illustrate the process of prey switching increase the likelihood of parasitic infections of the prey cause the overall health of the prey population to decrease parasitism commensalism mimicry mutualism Polar bears are the top predator influencing the abundance of seals and sea lions in a region. Hermit crabs inhabit the abandoned shells of marine snails that died long ago. Fungus-plant root associations benefit most of the plants living in a prairie. Mosquitoes function as a vector in the widespread transmission of malaria to people living in Ecuador. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 3 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 23 Part A In examining a terrestrial food web, we expect that the _____. ANSWER: Chapter 6 Reading Quiz Question 22 Part A Energy is lost as it moves from one trophic level to the next because _____. ANSWER: Chapter 6 Reading Quiz Question 11 Part A The research on the reintroduction of wolves into Yellowstone National Park reveals that in this ecosystem, wolves represent _____. ANSWER: mutualism predation parasitism commensalism biomass of primary consumers exceeds the biomass of producers number of secondary consumers exceeds the number of producers biomass of primary consumers exceeds the biomass of secondary consumers number of tertiary consumers exceeds the number of secondary consumers one trophic level does not consume the entire trophic level below it some of the calories consumed drive cellular activities and do not add mass some ingested materials are undigested and eliminated All of the listed responses are correct. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 4 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 10 Part A Overhunting of deer followed by a very difficult winter caused the deer population on an island to drop by 80%. In the next two years, visitors to the island were surprised to see many young trees sprouting up at the edges of the forest. This change in the number of saplings as a result of the decline of the deer population represents _____. ANSWER: Chapter 6 Reading Quiz Question 24 Part A The May 18, 1980, eruption of Mount Saint Helens blasted away soil and produced massive mudflows that scoured the adjacent region down to bare rock. Pumice rock that covered the area is eroding down to smaller gravel. This situation represents _____. ANSWER: Chapter 6 Reading Quiz Question 15 Part A In some ecosystems, succession increases the chance of disturbance. In these ecosystems, _____. a keystone producer a keystone herbivore a vital primary consumer a keystone predator a trophic cascade a decline in trophic level efficiency the emergence of a new ecological community a loss of a trophic level from a food web primary succession with the removal of all ecological legacies secondary succession with the removal of all ecological legacies secondary succession with several ecological legacies primary succession with several ecological legacies Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 5 of 7 5/21/2014 8:01 PM ANSWER: Chapter 6 Reading Quiz Question 12 Part A A forest is logged, leaving behind the seeds and saplings of many shrubs and trees. These seeds and saplings represent _____. ANSWER: Chapter 6 Reading Quiz Question 13 Part A During primary succession, populations of different species replace one another over time because of _____. ANSWER: Chapter 6 Reading Quiz Question 14 Part A Which one of the following represents a climax community in southern Alaska? ANSWER: ecosystems begin again with primary succession climax communities are expected climax communities may not occur disturbances usually result in virtually no ecological legacy ecological legacies a climax community primary succession pioneer species migration facilitation competition All of the listed responses are correct. Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 6 of 7 5/21/2014 8:01 PM Chapter 6 Reading Quiz Question 9 Part A In general, _____. ANSWER: Score Summary: Your score on this assignment is 0.0%. You received 0 out of a possible total of 19 points. the group of species associated with a white spruce forest lichens and mosses that colonize exposed rock birch and alder trees herbs and a few low shrubs that replace lichens and mosses food webs usually have 8-10 trophic levels food webs are interconnected food chains food chains consist of many interrelated food webs food webs consist of either consumers or producers Chapter 06 Reading Questions http://session.masteringenvironmentalscience.com/myct/assignmentPrintV… 7 of 7 5/21/2014 8:01 PM

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