1. D
2. D
3. D
4. C
5. A
6. C
7. A
8. C
9. C
10. B
11. C
12. B
13. A
14. E
15. B
16. A
17. A
18. C
19. C
20. B
21. B
22. D
23. C
24. B
25. A
26. B
27. C
28. E
29. B
30. C
31. B
32. B
33. E
34. C
35. A
36. C
37. C
38. C
39. C
40. D
41. B
42. A
43. B
44. C
45. C
46. D
47. C
48. B
49. D
50. B
ESSAY Questions
77. Speed is the rate at which an object covers distance. Velocity is speed in a direction. When you get in a car and travel on a highway at 90 km/hr S.
78. Acceleration is the rate of change of velocity. Since velocity has both speed and direction, if the direction of a moving object changes, as in rounding a corner, then the object is accelerating.
79. The acceleration due to gravity on Earth is 10 m/s^2. On the moon, it is roughly one sixth of that, or 1.6 m/s^2. This means that when an object falls straight down on Earth, it gains 10 m/s of speed in each second. On the moon it gains a speed of 1.6 m/s^2 each second.
80. Aristotle thought there were two kinds of motion - natural and violent. Natural motion referred to things falling and moving through space. Violent motion referred to motion under imposed forces. Copernicus thought that Earth moves around the sun. Galileo developed the modern ideas of force and inertia. Force is needed to change motion.
81. The law of inertia says that an object in motion will continue in its state of motion unless an outside force acts on it. This means that a book at rest on a table will stay at rest on the table until someone or something picks it up, bumps it, or in some other way forces it to move. It also means that once we throw a ball in deep space, the ball will continue in a straight line until it runs into something.
82. Mass generally refers to the quantity of matter in an object, whereas weight is the force due to gravity on an object. The mass of an object is the more basic quantity, for it is the same regardless of gravity. For example, 1 1 kg. brick has a mass of 1 kg on Earth, 1 kg on the moon, and 1 kg in deep space. Its weight, however, is 10 N on Earth, 1.6 N on the moon, and 0 N in deep space.
83. You, the coin, and the air are all moving horizontally at the same speed. When you flip a coin into the air, it will continue moving horizontally at that speed (Newton's first law).
TRUE/FALSE Answers
51. T
52. F
53. T
54. F
55. T
56. F
57. F
58. T
59. F
60. F
61. T
62. F
63. F
64. T
65. T
66. T
67. F
68. F
69. F
70. F
71. F
72. F
73. F
74. T
75. T
76. T