Answers to even questions in Chapter 5.   Notify me of any disagreement.

2.  The depth of the well is 30.6 m.

4.  The work done by the shopper is 1.6 kJ.

6.  a) The work done by the applied force is 31.9 J.
    b) The work done by the normal force is 0 J.
    c) The work done by the force of gravity is 0 J.
    d) The work done by the net force on the block is 31.9 J.

8.  The required speed of the ping-pong ball is 160 m/s.

10. a) The kinetic energy at point A is 1.2 J.
    b) The speed at point B is 5.0 m/s.
    c) The total work done is 6.3 J.

12. The kinetic energy of the ball at its highest point is 90.0 J.

14. a) The work done by the gravitational force is -168 J.
    b) The work done by the 100-N applied force is 500 J.
    c) The change in kinetic energy of the crate is 148 J.
    d) The final speed of the crate is 5.64 m/s.

16. The distance the sled moves before coming to rest is 2.0 m.

18. a) The ball's gravitational potential relative to the ceiling is -19.6 J.
    b) The ball's gravitational potential relative to the floor is 39.2 J.
    c) The ball's gravitational potential relative to a point at the same
       elevation as the ball is 0 J.

20. The speed of the ball upon release is 26.5 m/s.

22. The pole vaulter's altitude as she crosses the bar is 5.1 m/s.

24. a) The speed of the bead at B is 9.90 m/s.
    b) The speed of the bead at C is 7.67 m/s.

26. a) His speed at the bottom of his swing, starting from rest, is 10.9 m/s.
    b) His speed at the bottom of his swing, starting at 4.00 m/s, is 11.6 m/s.

28. a) The spring constant is 544 N/m.
    b) The speed of the projectile when x=0 is 19.7 m/s.

30. The maximum height of the block above the point of release is 10.2 m.

32. The change in kinetic energy of the box is 895 J.

34. The speed of the plane after 500 m of flight under thrust is 77 m/s.

36. a) The child's speed at the lowest position is 2.29 m/s.
    b) The mechanical energy lost due to friction is 15.6 J (ie W_nc -15.6 J).

38. The speed of the third mass after it has moved 4.0 m is 4.26 m/s.

40. The monkey and sled move 1.5 m up the incline.

42. a) The average speed of the climber is 0.408 m/s.
    b) The work done by the climber is 2.45 kJ.

44. a) The work done on the car is 75.0 kJ.
    b) The average power delivered by the engine is 33.5 hp.
    c) The instantaneous power delivered at t=2.0 s is 44.7 hp.

46. a) The average power delivered by elevator motor is 5.91 kW.
    b) The average power delivered during an upward cruise is 11.2 kW.

48. As the car comes to rest, frictional forces turn the car's kinetic energy
    into heat.

50. a) The speed of the man as he strikes the pavement is 4.43 m/s.
    b) The average force exerted by the ground is 147 kN.

52. a) The speed of the masses as they pass each other is 3.13 m/s.
    b) Their speed when the 5.00-kg mass hits the floor is 4.43 m/s.
    c) The additional height travelled by the 3.00-kg mass is 1.00 m.

54. See solution for details.

56. a) The average power developed by the engine is 42 hp.
    b) The instantaneous power developed at t=15 s is 85 hp.

58. a) The spring constant k is 98 N/m.
    b) The mass lands 1.2 m from the right hand edge of the incline.

60. a) The maximum compression of the spring is 0.15 m.
    b) If the putty is dropped, the maximum compression is 0.57 m.

62. a) The maximum compression of the spring on the right is 0.113 m.
    b) The block eventually comes to rest 0.074 m to the right of point A.

64. The launch speed of a 0.100-kg ball is 1.68 m/s.

66. a) The final speed of the diver is 24.5 m/s.
    b) At 55 mph, this seems too fast for safety.
    c) For a final speed of 5.00 m/s the parachute should be opened at 206 m.
    d) Existence of a terminal velocity shows that air drag depends on speed.

68. The coefficient of kinetic friction is 0.115.

70. a) See solution for details.
    b) The initial speed of the cart is 2.06 m/s.