1. Which one of the following situations is an example of an object with a non-zero kinetic energy?

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1 Name: Date: 1. Which one of the following situations is an example of an object with a non-zero kinetic energy? A) a drum of diesel fuel on a parked truck B) a stationary pendulum C) a satellite in geosynchronous orbit D) a car parked at the top of a hill E) a boulder resting at the bottom of a cliff 2. In which one of the following situations will there be an increase in kinetic energy? A) A projectile approaches its maximum height. B) A child pushes a merry go round causing it to rotate faster. C) A box is pulled across a rough floor at constant speed. D) A satellite travels in a circular orbit around the earth at fixed altitude. E) A stone at the end of a string is whirled in a horizontal circle at constant speed. 3. Which one of the following has the largest kinetic energy? A) a raindrop falling B) a woman swimming C) a jet airplane flying at its maximum speed D) the earth moving in its orbit around the sun E) the space shuttle orbiting the Earth 4. In which one of the following situations is zero net work done? A) A ball rolls down an inclined plane. B) A physics student stretches a spring. C) A projectile falls toward the surface of Earth. D) A box is pulled across a rough floor at constant velocity. E) A child pulls a wagon across a rough surface causing it to accelerate. 5. Which one of the following choices is an example of a non-conservative force? A) gravitational force B) electrical force C) kinetic frictional force D) elastic spring force Page 1

2 6. How much energy is dissipated in braking a 1000-kg car to a stop from an initial speed of 20 m/s? A) J B) J C) J D) J E) J 7. A constant force of 25 N is applied as shown to a block which undergoes a displacement of 7.5 m to the right along a frictionless surface while the force acts. What is the work done by the force? A) zero joules B) +94 J C) 94 J D) +160 J E) 160 J 8. During the construction of a high rise building, 40-kg block is vertically lifted 20 meters from the surface of the earth. To one significant figure, what is the change in the gravitational potential energy of the block? A) +800 J B) 800 J C) J D) 8000 J E) zero joules Use the following to answer question 9: A 10.0-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure. Page 2

3 9. While the crate slides along the upper surface, how much gravitational potential energy does it have compared to what it would have on the lower surface? A) 30 J B) 80 J C) 140 J D) 290 J E) 490 J 10. Larry's gravitational potential energy is 1870 J as he sits 2.20 m above the ground in a sky diving airplane. What is Larry's gravitational potential energy when be begins to jump from the airplane at an altitude of 923 m? A) J B) J C) J D) J E) J Use the following to answer question 11: A 2.0-kg projectile is fired with initial velocity components vox = 30 m/s and voy = 40 m/s from a point on the earth's surface. Neglect any effects due to air resistance. 11. How much work was done in firing the projectile? A) 900 J B) 1600 J C) 2500 J D) 4900 J E) 9800 J Use the following to answer question 12: A 10.0-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure. Page 3

4 12. What is the speed of the crate when it arrives at the lower surface? A) 7.7 m/s B) 8.6 m/s C) 59 m/s D) 75 m/s E) 98 m/s 13. A skier leaves the top of a slope with an initial speed of 5.0 m/s. Her speed at the bottom of the slope is 13 m/s. What is the height of the slope? A) 1.1 m B) 4.6 m C) 6.4 m D) 7.3 m E) 11 m 14. A 3.0-kg cylinder falls from rest through a distance of 6.0 m in an evacuated tube near the surface of the earth. What is its speed after the cylinder has fallen the 6.0 m distance? A) 8.0 m/s B) 11 m/s C) 13 m/s D) 120 m/s E) 26 m/s 15. A force of magnitude 25 N directed at an angle of 37 above the horizontal moves a 10-kg crate along a horizontal surface at constant velocity. How much work is done by this force in moving the crate a distance of 15 m? A) zero joules B) 1.7 J C) 40 J D) 98 J E) 300 J Page 4

5 Use the following to answer question 16: Chapter 6-7 Review A 10.0-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure. 16. What minimum coefficient of kinetic friction is required to bring the crate to a stop over a distance of 5.0 m along the lower surface? A) 0.30 B) 0.32 C) 0.60 D) 0.66 E) Which one of the following statements concerning kinetic energy is true? A) Kinetic energy can be measured in watts. B) Kinetic energy is always equal to the potential energy. C) Kinetic energy is always positive. D) Kinetic energy is a quantitative measure of inertia. E) Kinetic energy is directly proportional to velocity. 18. A block is dropped from a high tower and is falling freely under the influence of gravity. Which one of the following statements is true concerning this situation? Neglect air resistance. A) As the block falls, the net work done by all of the forces acting on the block is zero joules. B) The kinetic energy increases by equal amounts over equal distances. C) The kinetic energy of the block increases by equal amounts in equal times. D) The potential energy of the block decreases by equal amounts in equal times. E) The total energy of the block increases by equal amounts over equal distances. Page 5

6 19. A tennis ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward. Which statement is true concerning this situation? A) The momentum of the ball and the momentum of the earth both change. B) Neither the momentum of the ball nor the momentum of the earth changes. C) The momentum of the ball is changed; the momentum of the earth is not changed. D) The momentum of the ball is unchanged; the momentum of the earth is changed. E) Both the momentum and the kinetic energy of the ball change because of the collision. 20. In which one of the following situations is linear momentum not conserved? A) A bomb suspended by a string explodes into one hundred fragments. B) A bowling ball collides with a set of ten pins. C) A golf ball is struck by a club. D) An astronaut floating in space throws a hammer away and subsequently moves in the opposite direction. E) A tree limb is struck by lightning and falls to the ground. 21. A kg marble moving to the right at 0.40 m/s has a head-on, elastic collision with a kg marble sitting at rest on a smooth, level surface. Which of the following are the correct magnitudes and directions of the velocities of the two marbles after the collision? kg marble kg marble A) 0.15 m/s, left 0.25 m/s, right B) 0.10 m/s, right 0.30 m/s, right C) zero m/s 0.25 m/s, right D) 0.20 m/s, left 0.20 m/s, right E) 0.40 m/s, left zero m/s 22. Two objects of equal mass traveling toward each other with equal speeds undergo a head on collision. Which one of the following statements concerning their velocities after the collision is necessarily true? A) They will exchange velocities. B) Their velocities will be reduced. C) Their velocities will be unchanged. D) Their velocities will be zero. E) Their velocities may be zero. Page 6

7 23. A 160-kg space probe is moving in the positive x direction at 18 km/s when it encounters a time-dependent force directed in the negative x direction. The force is as follows: Determine the final speed of the space probe. A) 8.6 km/s B) 5.3 km/s C) 11 km/s D) 16 km/s E) 23 km/s 24. A 3.0-kg cart moving to the right with a speed of 1.0 m/s has a head-on collision with a 5.0-kg cart that is initially moving to the left with a speed of 2.0 m/s. After the collision, the 3.0-kg cart is moving to the left with a speed of 1.0 m/s. What is the final velocity of the 5.0-kg cart? A) zero m/s B) 0.80 m/s to the right C) 0.80 m/s to the left D) 2.0 m/s to the right E) 2.0 m/s to the left 25. Complete the following statement: Momentum will be conserved in a two-body collision only if A) both bodies come to rest. B) the collision is perfectly elastic. C) the kinetic energy of the system is conserved. D) the net external force acting on the two-body system is zero. E) the internal forces of the two body system cancel in action-reaction pairs. 26. The head of a hammer (m = 1.5 kg) moving at 4.5 m/s strikes a nail and bounces back with the same speed after an elastic collision lasting s. What is the magnitude of the average force the hammer exerts on the nail? A) 6.8 N B) 60 N C) 90 N D) 180 N E) 240 N Page 7

8 Use the following to answer question 27: Chapter 6-7 Review A comet fragment of mass kg is moving at m/s when it crashes into Callisto, a moon of Jupiter. The mass of Callisto is kg. The collision is completely inelastic. 27. How much kinetic energy was released in the collision? A) J B) J C) J D) J E) J 28. A football player kicks a 0.41-kg football initially at rest; and the ball flies through the air. If the kicker's foot was in contact with the ball for s and the ball's initial speed after the collision is 21 m/s, what was the magnitude of the average force on the football? A) 9.7 N B) 46 N C) 81 N D) 170 N E) 210 N 29. A 0.10-kg cart traveling in the positive x direction at 10.0 m/s collides with a 0.30-kg cart at rest. The collision is elastic. What is the velocity of the 0.10-kg cart after the collision? A) +2.5 m/s B) 2.5 m/s C) +5 m/s D) 5 m/s E) +3.3 m/s 30. A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on a large, air-filled bag. Which one of the following best describes why no injury occurs? A) The bag provides the necessary force to stop the person. B) The bag reduces the impulse to the person. C) The bag increases the amount of time the force acts on the person and reduces the change in momentum. D) The bag decreases the amount of time during which the momentum is changing and reduces the average force on the person. E) The bag increases the amount of time during which the momentum is changing and reduces the average force on the person. Page 8

9 Answer Key Chapter 6-7 Review 1. C 2. B 3. D 4. D 5. C 6. B 7. C 8. C 9. D 10. A 11. C 12. B 13. D 14. B 15. E 16. E 17. C 18. B 19. A 20. E 21. D 22. E 23. A 24. C 25. D 26. D 27. D 28. D 29. D 30. E Page 9