Chapter 6

1. Chapter 6 Momentum

2. When a farmer throws a 3-kg pumpkin at a speed of 4 m/s onto a compost pile, the pumpkin’s momentum just before hitting the pile is a. 0 kg•m/s. b. 5 kg•m/s. c. 7 kg•m/s. d. 12 kg•m/s.

3. When a farmer throws a 3-kg pumpkin at a speed of 4 m/s onto a compost pile, the pumpkin’s momentum just before hitting the pile is a. 0 kg•m/s. b. 5 kg•m/s. c. 7 kg•m/s. d. 12 kg•m/s.

4. Compared with the momentum of a 200-lb man running 10 mi/h, the momentum of a 2000-lb car moving 1 mph is a. zero. b. the same. c. greater. d. less.

5. Compared with the momentum of a 200-lb man running 10 mi/h, the momentum of a 2000-lb car moving 1 mph is a. zero. b. the same. c. greater. d. less.

6. A lunar vehicle is tested on Earth at a speed of 10 km/h. When it travels at the same speed on the Moon, its momentum is a. the same. b. less. c. more. d. zero.

7. A lunar vehicle is tested on Earth at a speed of 10 km/h. When it travels at the same speed on the Moon, its momentum is a. the same. b. less. c. more. d. zero.

8. When both the force and time of contact are doubled, the impulse on an object is a. unchanged. b. doubled. c. quadrupled. d. decreased.

9. When both the force and time of contact are doubled, the impulse on an object is a. unchanged. b. doubled. c. quadrupled. d. decreased.

10. Your friend says that impulse equals momentum. Your friend’s statement is not correct, and the missing word is a. work. b. acceleration. c. speed or velocity. d. change.

11. Your friend says that impulse equals momentum. Your friend’s statement is not correct, and the missing word is a. work. b. acceleration. c. speed or velocity. d. change.

12. If a car comes to a full stop when hitting a haystack and when hitting a stone wall, the change in momentum is greater for hitting the a. haystack. b. stone wall. c. Same momentum change in both cases. d. None of the above.

13. If a car comes to a full stop when hitting a haystack and when hitting a stone wall, the change in momentum is greater for hitting the a. haystack. b. stone wall. c. Same momentum change in both cases. d. None of the above.

14. A 1-kg ball has the same speed as a 10-kg ball. Compared with the 1-kg ball, the 10-kg ball has • less momentum. • the same momentum. • 10 times as much momentum. • 100 times as much momentum.

15. A 1-kg ball has the same speed as a 10-kg ball. Compared with the 1-kg ball, the 10-kg ball has • less momentum. • the same momentum. • 10 times as much momentum. • 100 times as much momentum.

16. Which of the following equations most directly illustrates the safety value of automobile airbags? a. F = ma. b. Ft = ∆(mv). c. d = 1/2 at2. d. v = gt.

17. Which of the following equations most directly illustrates the safety value of automobile airbags? a. F = ma. b. Ft = ∆(mv). c. d = 1/2 at2. d. v = gt.

18. A ball is tossed into a bale of hay and comes to a stop. If instead, it comes to a stop when hitting a sticky solid wall, the impulse needed to stop it is a. less. b. the same. c. more. d. zero.

19. A ball is tossed into a bale of hay and comes to a stop. If instead, it comes to a stop when hitting a sticky solid wall, the impulse needed to stop it is a. less. b. the same. c. more. d. zero.

20. When a falling object bounces as it hits the ground a. the impulse on it is greater than for stopping it. b. its change in momentum is greater than for stopping. c. Both of these. d. None of these.

21. When a falling object bounces as it hits the ground a. the impulse on it is greater than for stopping it. b. its change in momentum is greater than for stopping. c. Both of these. d. None of these.

22. When you jump from an elevated position to the ground below, the force you experience when landing does NOT depend on a. the jumping height. b. the softness or hardness of the ground. c. how much you bend your knees. d. your attitude about jumping.

23. When you jump from an elevated position to the ground below, the force you experience when landing does NOT depend on a. the jumping height. b. the softness or hardness of the ground. c. how much you bend your knees. d. your attitude about jumping.

24. Nets used to catch falling boulders on the side of rocky hillside roadways are more effective than rigid fences because their breakage is reduced by a. less impulse of falling rocks. b. less momentum of falling rocks. c. more time to change the momentum of falling rocks. d. less time to change the momentum of falling rocks.

25. Nets used to catch falling boulders on the side of rocky hillside roadways are more effective than rigid fences because their breakage is reduced by a. less impulse of falling rocks. b. less momentum of falling rocks. c. more time to change the momentum of falling rocks. d. less time to change the momentum of falling rocks.

26. When you say momentum is conserved, you mean that a. when an impulse acts on an object, its momentum will change. b. momentum can be stored. c. when external impulses don’t occur, a system’s momentum remains the same before and after an interaction. d. when two objects collide, the mass and velocity of each object will not change.

27. When you say momentum is conserved, you mean that a. when an impulse acts on an object, its momentum will change. b. momentum can be stored. c. when external impulses don’t occur, a system’s momentum remains the same before and after an interaction. d. when two objects collide, the mass and velocity of each object will not change.

28. In the absence of external forces, momentum is conserved in a. an elastic collision. b. an inelastic collision. c. either an elastic or an inelastic collision. d. neither an elastic nor an inelastic collision.

29. In the absence of external forces, momentum is conserved in a. an elastic collision. b. an inelastic collision. c. either an elastic or an inelastic collision. d. neither an elastic nor an inelastic collision.

30. A pair of spiral galaxies collide and merge to form one larger elliptical galaxy. Astronomers assume that the momentum of the new elliptical galaxy is • equal to the sum of the momenta of two spiral galaxies. • equal to the difference in momenta of the two spiral galaxies. • the same as the momentum of the more massive spiral galaxy. • zero.

31. A pair of spiral galaxies collide and merge to form one larger elliptical galaxy. Astronomers assume that the momentum of the new elliptical galaxy is • equal to the sum of the momenta of two spiral galaxies. • equal to the difference in momenta of the two spiral galaxies. • the same as the momentum of the more massive spiral galaxy. • zero.