Work & Energy review sheet Name: 1. 2. Date: How much work is required to lift a 2-kilogram mass to a height of 10 meters? A. 5 joules B. C. 100 joules D. 200 joules A B C D A. 4. 5. 20 joules Four machines do the amounts of work listed in the table shown. The time they take to do the work is also listed. Which machine develops the most power? Machine 3. 6. A Work Time 1,000 joules 10 sec 2,000 joules 10 sec 1,000 joules 2,000 joules B. B 7. 5 sec 5 sec C. C 8. D. D A garden tractor drags a plow with a force of 500 newtons a distance of 10 meters in 20 seconds. How much work is done? A. 25 joules B. C. 2,500 joules D. 5,000 joules 9. 1,000 joules As the length of time it takes a student to swim 100 meters decreases, the power developed by the student A. decreases C. remains the same B. 10. increases How much work is done on a 300-newton suitcase to lift it 0.50 meter? A. 600 joules B. C. 150 joules D. 75 joules 11. 300 joules A machine is able to do 30 joules of work in 6.0 seconds. The power developed by the machine is A. 0.20 watt B. C. 5.0 watts D. 180 watts What force is required to do 60 joules of work in sliding an object a distance of 10 meters across a level oor? A. 6 newtons B. C. 60 newtons D. 600 newtons 10 newtons How much work will a 500-watt motor do in 10 seconds? A. 0.02 joule B. C. 500 joules D. 5,000 joules 50 joules How much work is done when a rock weighing 10 newtons is lifted a vertical distance of 8 meters? A. 18 joules B. C. 80 joules D. 800 joules 2 joules How long would it take a machine to do 5,000 joules of work if the power rating of the machine is 100 watts? A. 5,000 sec B. C. 10 sec D. 0.2 sec 50 sec The work done on a 10.0-kilogram mass to give it a speed of 5.00 meters per second is A. page 1 0.50 watt 50.0 J B. 2.00 J C. 125 J D. 2500 J Work & Energy review sheet 12. 13. 16. Car A and car B of equal mass travel up a hill. Car A moves up the hill at a constant speed that is twice the constant speed of car B. Compared to the power developed by car B, the power developed by car A is A. the same B. twice as much C. half as much D. four times as much 5J B. C. 11 J D. 50 J A. 10 J B. 60 J C. 80 J D. 100 J In the diagram, 55 joules of work is needed to raise a 10-newton 5.0 meters. How much work is done to overcome friction as the weight is raised? A. A 20-newton block is at rest at the bottom of a frictionless incline as shown in the diagram. How much work must be done against gravity to move the block to the top of the incline? 17. 5.5 J Work is being done when a force A. acts vertically on a cart that can only move horizontally B. is exerted by one team in a tug of war when there is no movement C. is exerted while pulling a wagon up a hill D. of gravitational attraction acts on a person standing on the surface of the Earth 18. 14. 15. One joule is equivalent to one A. newton meter3 B. kilogram meter3 C. watt2 newton D. kilogram meter2 second2 Car A and car B are of equal mass and travel up a hill. Car A moves up the hill at a constant speed that is twice the constant speed of car B. Compared to the power developed by car B, the power developed by car A is A. the same B. C. half as much D. four times as much The graph shows the force exerted on a block as a function of the block's displacement in the direction of the force. How much work did the force do in displacing the block 5.0 meters? A. 19. twice as much B. 20 J C. 0.80 J D. 4.0 J A motor has an output of 1,000 watts. When the motor is working at full capacity, how much time will it require to lift a 50-newton weight 100 meters? A. page 2 0J 5s B. 10 s C. 50 s D. 100 s Work & Energy review sheet 20. 21. A 6:0 102 -newton man climbing a rope at a speed of 2.0 meters per second develops power at the rate of A. 1:2 101 W B. 6:0 102 W C. 3:0 102 W D. 1:2 103 W 22. As shown in the diagram, pulling a 9.8-newton cart a distance of 0.50 meter along a plane inclined at 15 requires 1.3 joules of work. If the cart were raised 0.50 meter vertically instead of being pulled along the inclined plane, the amount of work would be A. less B. greater C. the same A student performs a laboratory activity in which a 15-newton force acts on a 2.0-kilogram mass. The work done over time is summarized in the table shown. DATA TABLE Time (s) Work (J) 1.0 32 3.0 89 0 2.0 4.0 0 59 120 a) Using the information in the data table, construct a graph on a grid, following the directions given. 1) Develop an appropriate scale for work and plot the points for a work-versus-time graph. 2) Draw the best- t line. b) Calculate the value of the slope of the graph constructed in the previous part. (Show all calculations, including equations and substitutions with units.) c) Based on your graph, how much time did it take to do 75 joules of work? page 3 Work & Energy review sheet 23. 26. A student running up a ight of stairs increases her speed at a constant rate. Which graph best represents the relationship between work and time for the student's run up the stairs? A. B. C. D. The diagram pictured shows a worker moving a 50.0-kilogram safe up a ramp by applying a constant force of 300 newtons parallel to the ramp. The data table shows the position of the safe as a function of time. Time (s) 0.0 Distance Moved up the Ramp (m) 0.0 2.0 4.6 1.0 24. A net force of 5.0 newtons moves a 2.0-kilogram object a distance of 3.0 meters in 3.0 seconds. How much work is done on the object? A. 25. 1.0 J B. 10 J C. 15 J 3.0 4.0 5.0 2.2 6.6 8.6 11.0 D. 30 J The diagram shows a 1:0 103 -newton crate to be lifted at constant speed from the ground to a loading dock 1.5 meters high in 5.0 seconds. What power is required to lift the crate? A. 1:5 103 W B. 2:0 102 W C. 3:0 102 W D. 7:5 103 W Using the information in the data table, construct a line graph. Plot the data points and draw the best- t line. page 4 Work & Energy review sheet 27. Using one or more complete sentences, explain the physical signi cance of the slope of the graph. 28. Calculate the work done by the worker in the rst 3.0 seconds. [Show all calculations, including the equation and substitution with units.] 29. How much work is done on a downhill skier by an average braking force of 9:8 102 newtons to stop her in a distance of 10 meters? 30. A. 1:0 101 J B. 9:8 101 J C. 1:0 103 J D. 9:8 103 J 31. The accompanying diagram shows two identical wooden planks, A and B, at di erent incline angles, used to slide concrete blocks from a truck. The accompanying graph represents the elongation of a spring as a function of the applied force. How much work must be done to stretch the spring 0.40 meter? A. 32. Compared to the amount of work done against friction by a block sliding down plank A, the work done against friction by a block sliding down plank B is A. less B. more C. the same page 5 4.8 J B. 6.0 J C. 9.8 J D. 24 J Which combination of units can be used to express work? newton meter second A. newton second meter B. C. newton/meter D. newton meter Work & Energy review sheet 33. 34. In the accompanying diagram, 400. joules of work is done raising a 72-newton weight a vertical distance of 5.0 meters. Base your answer(s) to the following question(s) on the information and diagram below. A 160.-newton box sits on a 10.-meter-long frictionless plane inclined at an angle of 30. to the horizontal as shown. Force (F) applied to a rope attached to the box causes the box to move with a constant speed up the incline. Calculate the amount of work done in moving the box from the bottom to the top of the inclined plane. [Show all work, including the equation and substitution with units.] How much work is done to overcome friction as the weight is raised? A. 40. J B. 360 J C. 400. J D. 760 J page 6 Work & Energy review sheet 35. 36. Base your answer(s) to the following question(s) on the information below and on your knowledge of physics. Using a spring toy like the one shown in the diagram, a physics teacher pushes on the toy, compressing the spring, causing the suction cup to stick to the base of the toy. A 3.0-kilogram block is initially at rest on a frictionless, horizontal surface. The block is moved 8.0 meters in 2.0 seconds by the application of a 12-newton horizontal force, as shown in the accompanying diagram. What is the average power developed while moving the block? A. When the teacher removes her hand, the toy pops straight up and just brushes against the ceiling. She does this demonstration ve times, always with the same result. 37. 24 W B. 32 W C. 48 W D. 96 W The diagram below shows points A, B, and C at or near Earth's surface. As a mass is moved from A to B, 100. joules of work are done against gravity. When the teacher repeats the demonstration for the sixth time the toy crashes against the ceiling with considerable force. The students notice that in this trial, the spring and toy separated from the base at the moment the spring released. The teacher puts the toy back together, repeats the demonstration and the toy once again just brushes against the ceiling. What is the amount of work done against gravity as an identical mass is moved from A to C? Describe the conversions that take place between pairs of the three forms of mechanical energy, beginning with the work done by the teacher on the toy and ending with the form(s) of energy possessed by the toy as it hits the ceiling. [Neglect friction.] A. page 7 100. J B. 173 J C. 200. J D. 273 J Work & Energy review sheet 38. 40. A box is pushed to the right with a varying horizontal force. The graph below represents the relationship between the applied force and the distance the box moves. Base your answer(s) to the following question(s) on the information below. A boy pushes his wagon at constant speed along a level sidewalk. The graph below represents the relationship between the horizontal force exerted by the boy and the distance the wagon moves. Force vs.Distance What is the total work done in moving the box 6.0 meters? A. 39. 9.0 J B. 18 J C. 27 J D. 36 J What is the total work done by the boy in pushing the wagon 4.0 meters? As shown in the diagram below, a child applies a constant 20.-newton force along the handle of a wagon which makes a 25 angle with the horizontal. A. 41. How much work does the child do in moving the wagon a horizontal distance of 4.0 meters? A. 5.0 J B. 34 J C. 73 J D. 80. J page 8 5.0 J B. 7.5 J C. 120 J D. 180 J Which is an SI unit for work done on an object? A. kg m2 s2 B. kg m2 s C. kg m s2 D. kg m s Work & Energy review sheet 42. 45. The diagram here shows a 1-kilogram aluminum sphere and a 3-kilogram copper sphere of equal radius located 20 meters above the ground. If the two spheres are allowed to fall freely to the ground, they will experience the same 46. A. acceleration B. decrease in potential energy C. increase in kinetic energy A 75-kilogram boy initially at rest skis down the slope as shown. Assuming no frictional loss, what will be his kinetic energy at the bottom of the slope? A. 1,500 joules B. C. 15,000 joules D. 75,000 joules The diagram shows a cart at four positions as it moves along its track. At which positions is the sum of the potential energy and kinetic energy of the cart the same? D. speci c gravity 43. A pendulum swings as shown in the diagram. At which position is the kinetic energy of the pendulum bob least? A. A B. C. C D. D B A. decreases C. remains the same B. A. A and B, only B. B and C, only C. C and D, only D. all positions, A through D 44. As a falling apple approaches the ground, its potential energy increases page 9 7,500 joules Work & Energy review sheet 47. 50. The diagram here shows a 1-kilogram stone being dropped from a bridge 100 meters above a gorge. Each of the blocks in the diagrams is lifted vertically for the distance indicated. Which block will gain the most gravitational potential energy? A. B. As the stone falls, the gravitational potential energy of the stone 48. A. decreases C. remains the same B. increases C. As a pendulum moves from the bottom of its swing to the top of its swing, the A. kinetic energy of the pendulum increases B. kinetic energy of the pendulum remains the same C. potential energy of the pendulum decreases D. D. potential energy of the pendulum increases 49. An object with a mass of 10.0 kilograms is moving at a speed of 5.00 meters per second. The kinetic energy of the mass is A. 50.0 joules B. C. 125 joules D. 250 joules 51. 2.00 joules page 10 As a pendulum travels from the highest point of its swing to the lowest point of its swing, its potential energy A. decreases C. remains the same B. increases Work & Energy review sheet 52. 53. 54. The diagram shown here represents a block suspended from a spring. The spring is stretched 0.200 meter. If the spring constant is 200 newtons per meter, what is the weight of the block? A. 40.0 N B. C. 8.00 N D. 4.00 N As the pendulum swings from position A to position B as shown in the diagram, what is the relationship of kinetic energy to potential energy? [Neglect friction.] 20.0 N A 0.10-meter spring is stretched from equilibrium to position A and then to position B as shown in the diagram. Compared to the spring's potential energy at A, what is its potential energy at B ? A. The kinetic energy decrease is more than the potential energy increase. B. The kinetic energy increase is more than the potential energy decrease. C. The kinetic energy decrease is equal to the potential energy increase. D. The kinetic energy increase is equal to the potential energy decrease. 55. A. the same B. twice as great C. half as great D. four times as great 56. Which graph best represents the relationship between the kinetic energy (KE) of a moving object as a function of its velocity (v)? A. B. C. D. A basketball player who weighs 600 newtons jumps 0.5 meter vertically o the oor. What is her kinetic energy just before hitting the oor? A. page 11 30 J B. 60 J C. 300 J D. 600 J Work & Energy review sheet 57. A. 58. 60. When a 5-kilogram mass is lifted from the ground to a height of 10 meters, the gravitational potential energy of the mass is increased by approximately 0.5 J B. 2J C. 50 J D. 500 J Three people of equal mass climb a mountain using paths A, B, and C shown in the diagram. Along which path(s) does a person gain the greatest amount of gravitational potential energy from start to nish? The graph represents the relationship between the force applied to a spring and the elongation of the spring. What is the spring constant? A. A, only B. B, only C. C, only D. The gain is the same along all paths. 59. A. 20 N/m C. 0.80 N B. m 9.8 N/kg 61. D. 0.050 m/N An object 10 meters above the ground has Z joules of potential energy. If the object falls freely, how many joules of kinetic energy will it have gained when it is 5 meters above the ground? A. Z B. 2Z C. Z 2 D. 0 62. Which graph best represents the relationship between the elongation of an ideal spring and the applied force? A. B. C. D. A 20-kilogram object strikes the ground with 1,960 joules of kinetic energy after falling freely from rest. How far above the ground was the object when it was released? A. page 12 10 m B. 14 m C. 98 m D. 200 m Work & Energy review sheet 63. 65. Which graph below shown represents the relationship between the potential energy stored in a spring (PE) and the change in the length of the spring from its equilibrium position (X)? A. C. The diagram shown represents a frictionless track. A 10-kilogram block starts from rest at point A and slides along the track. B. As the block moves from point A to point B, the total amount of gravitational potential energy changed to kinetic energy is approximately D. A. Both potential energy and kinetic energy increase. B. Both potential energy and kinetic energy decrease. C. Potential energy increases and kinetic energy decreases. D. Potential energy decreases and kinetic energy increases. page 13 B. 20 J C. 50 J D. 500 J 66. The diagram pictured shows a spring compressed by a force of 6.0 newtons from its rest position to its compressed position. Calculate the spring constant for this spring. [Show all calculations, including equations and substitutions with units.] 67. An object with a speed of 20 meters per second has a kinetic energy of 400 joules. The mass of the object is 64. The diagram shows the path of a satellite in an elliptical orbit around the Earth. As the satellite moves from point A to point B, what changes occur in its potential and kinetic energies? A. 5J A. 1.0 kg B. 2.0 kg C. 0.50 kg D. 40 kg Work & Energy review sheet 68. 69. 70. Which variable expression is paired with a corresponding unit? A. mass distance time and watt B. mass distance2 time and watt C. mass distance2 time2 and joule D. mass distance time3 and joule The unstretched spring in the accompanying diagram has a length of 0.40 meter and a spring constant k. A weight is hung from the spring, causing it to stretch to a length of 0.60 meter. The diagram shows a 1.5-kilogram kitten jumping from the top of a 1.80-meter-high refrigerator to a 0.90-meter-high counter. Compared to the kitten's gravitational potential energy on top of the refrigerator, the kitten's gravitational potential energy on top of the counter is How many joules of elastic potential energy are stored in this stretched spring? 71. A. half as great B. C. one-fourth as great D. four times as great A. 0:020 C. 0:18 k k B. 0:080 D. 2:0 k k In the accompanying diagram, a student compresses the spring in a pop-up toy 0.020 meter. twice as great If the spring has a spring constant of 340 newtons per meter, how much energy is being stored in the spring? page 14 A. 0.068 J B. 0.14 J C. 3.4 J D. 6.8 J Work & Energy review sheet 72. 74. Base your answer(s) to the following question(s) on the information and diagram below, which is drawn to a scale of 1.0 centimeter = 3.0 meters. The accompanying diagram shows block A, having mass 2m and speed v, and block B having mass m and speed 2v. A 650-kilogram roller coaster car starts from rest at the top of the rst hill of its track and glides freely. [Neglect friction.] Compared to the kinetic energy of block A, the kinetic energy of block B is 75. Using one or more complete sentences, compare the kinetic energy of the car at the top of the second hill to its kinetic energy at the top of the third hill. 73. A. the same B. C. one-half as great D. four times as great Which graph best represents the elastic potential energy stored in a spring (PEs ) as a function of its elongation, x? A. Two vacationers walk out on a horizontal pier as shown in the accompanying diagram. B. As they approach the end of the pier, their gravitational potential energy will A. decrease C. remain the same B. C. increase D. page 15 twice as great Acces format version 4.4.158 c 1997{2011 EducAide Software _ Licensed for use by Problem-Attic Work & Energy review sheet 02/20/2013 1. Answer: D 21. Answer: 2. Answer: C 22. Answer: 3. Answer: D 4. Answer: B 5. Answer: C 6. Answer: C 7. Answer: A 8. Answer: D 9. Answer: 10. Answer: B [see answer sheet]; slope = Wt = 30 J=s, W J 120 J or xv = 120 4s or P = t = 4s = 30 W 2:5 s 0:3 s 23. Answer: B 24. Answer: C 25. Answer: C 26. 27. Answer: The slope is the average speed of the safe C 28. Answer: W=F B 29. Answer: D 11. Answer: C 30. Answer: B 12. Answer: B 31. Answer: A 13. Answer: A 32. Answer: D 14. Answer: D 33. Answer: A 15. Answer: B 34. Answer: 800 J 16. Answer: B 35. Answer: 17. Answer: C 18. Answer: B 19. Answer: A 20. Answer: D s; W = 1980 J work into or potential energy(spring) into or kinetic energy into or potential energy (gravity) 36. Answer: C 37. Answer: A 38. Answer: C Teacher's Key Page 2 39. Answer: C 61. Answer: B 40. Answer: C 62. Answer: A 41. Answer: A 63. Answer: B 42. Answer: A 64. Answer: D 43. Answer: D 65. Answer: D 44. Answer: A 66. Answer: F = kx; 60 N = k (0:040); k = 150N=m; 45. Answer: C 46. Answer: 67. Answer: B D 47. Answer: 68. Answer: C A 48. Answer: 69. Answer: A D 49. Answer: 70. Answer: A C 50. Answer: 71. Answer: A B 51. Answer: 72. Answer: The car's KE is less. A 52. Answer: 73. Answer: C A 53. Answer: 74. Answer: B D 54. Answer: 75. Answer: D D 55. Answer: C 56. Answer: C 57. Answer: D 58. Answer: A 59. Answer: C 60. Answer: D

© Copyright 2018