Fall Review Part B Key

fall review part b Answer Section SHORT ANSWER 1. ANS: swimming, track, soccer, speed skating, ski jump 2. ANS: SI 3. ANS: 60ºC 4. ANS: line graph 5. ANS: 353 K 6. ANS: 2, 3, 1, 5, 4

7. ANS: The two cars drove in different directions. 8. ANS: Yes, the skater could be changing directions. No, any change in speed will change the velocity. 9. ANS: The two cars are traveling in different directions. 10. ANS: Yes, it could have constant speed. No, a change in velocity is always an acceleration. 11. ANS: Velocity is the rate of change of position. Acceleration is the rate of change of velocity. 12. ANS: The car is slowing down at the rate of 5 m/s every second. 13. ANS: an unbalanced force is acting on it 14. ANS: 0, 0 15. ANS: Yes, the object could be moving at a constant velocity (not changing its motion). 16. ANS: An object in motion stays in motion unless an unbalanced force acts on it. An object at rest stays at rest unless an unbalanced force acts on it. 17. ANS: Your foot stops, but the inertia of the rest of your body keeps it going forward. 18. ANS: A seat belt helps to minimize injury from the inertia that keeps your body moving forward. 19. ANS: 4 20. ANS: 1 21. ANS: They are the same.

22. ANS: Object 2 has greater mass than object 1 and the same velocity. 23. ANS: its greater velocity 24. ANS: The rock supplies an upward reaction force on Sally equal to her weight. 25. ANS: 0.5 kg × m/s 26. ANS: Crumple the paper into a ball to reduce the air resistance. 27. ANS: All objects would fall at the same rate, but the flatter object has a greater air resistance and will not fall as fast, so it hits the ground last. 28. ANS: They will hit at the same time. Vertically, they travel the same distance under the influence of the same force, gravity; horizontal motion doesn't count. 29. ANS: Mass measures the amount of matter; weight measures the force of gravity on the matter. 30. ANS: Your mass is the same because you didn't change the amount of matter, but the gravitational force decreased, decreasing your weight. 31. ANS: hot gases are the action force, accelerating rocket is the reaction force 32. ANS: the gravitational force exerted on an object 33. ANS: After the chute opens, it increases the air resistance. This slows the sky diver to a terminal velocity where air resistance to the chute and diver are balancing the force of gravity. 34. ANS: ball loses momentum, pins gain momentum lost by ball 35. ANS: It decreases because the shuttle is farther from Earth. 36. ANS: D 37. ANS: C 38. ANS: Kinetic energy is based on mass and velocity. Given equal velocity, the dump truck has the most mass, so it has the most kinetic energy. The sports car would be next, and the bicycle last. 39. ANS: No, his machine would have an efficiency of 108 percent. No machine can have an efficiency greater than 100 percent. 40. ANS: Adding oil decreases friction, decreases work lost to heat, increases work output, and increases efficiency. 41. ANS: Divide the radius of the effort gear by the radius of the resistance gear. 42. ANS: Sally; Sally does the same amount of work in less time, so she is more powerful.

43. ANS: Ideal mechanical advantage doesn't take energy lost to friction into account. 44. ANS: It has NO UNITS; they divide out. 45. ANS: B, A, C 46. ANS: It is determined by the density of the medium at the compressions. 47. ANS: frequency increases; wavelength decreases 48. ANS: wavelength, frequency, and speed remain the same; amplitude increases 49. ANS: As the ripples move away from the original disturbance, they lose energy. 50. ANS: It means that one wave crest passes a given point every second. 51. ANS: When the hiker shouted, the sound waves traveled to the cliff and were reflected back to the listener's ears. 52. ANS: Both cause waves to bend. Refraction occurs when waves change speed when changing media. Diffraction occurs when waves bend around a barrier. 53. ANS: At the node, destructive interference takes place. At the crest (antinode), constructive interference takes place. PROBLEM 54. ANS: volume = 22 mL – 18 mL = 4 mL 55. ANS: d = 240 g/200 mL = 1.2 g/mL = 1.2 g/cm3 56. ANS: d = s x y = 227 km/h × (2.00 h) = 454 km 57. ANS: vf – vi/t = (96 m/s – 32 m/s)/ 8.0 s = 8.0 m/s2 58. ANS: 250 kg m/s p = mv = 10 kg 25 m/s = 250 kg m/s 59. ANS: 48 N F = ma = 12 kg 4 m/s2 = 48 kg m/s2 = 48 N 60. ANS: 1/2 mv2 = 1/2 (18 + 62)(7)2 = 1,960 J 61. ANS: 1/2 mv2 = 1/2 (20 + 50)(8)2 = 2,290 J 62. ANS: (m)(9.8)(h) = (70)(9.8)(3) = 2,058 J

63. ANS: (m)(9.8)(h) = (90)(9.8)(4) = 3,528 J 64. ANS: IMA = Le/Lr = 4.0 m/1.0 m = 4 65. ANS: IMA = Le/Lr = 2.0 m/1.0 m = 2 66. ANS: IMA = l/h = 12 m/4 m = 3 67. ANS: MA = R/F; R = MA F = 3 70 N = 210 N 68. ANS: W = F d = 70 N 12 m = 840 N/m = 840 J 69. ANS: 1,680 J Work = F × d; F = 2 × 70 N = 140 N; W = 140 N × 12 m = 1,680 N·m =1680 J 70. ANS: 210 N dr = de' Eff. = Fr/Fe;·Fe = Fr/E = 210 N/100% = 210 N 71. ANS: IMA = Le/Lr = 4.5 m/1.5 m = 3 72. ANS: IMA = Le/Lr = 24 cm/0.5 cm = 48 73. ANS: See figure 7-8 in the student text. 74. ANS: V = d/t = 4.4 m/2.0 s = 2.2 m/s 75. ANS: v = λf = 2.0 Hz × 10 m = 20 m/s COMPLETION 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90.

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velocity speed speed speed, direction negative acceleration initial, final balanced inertia (mass) acceleration Static rolling different change four

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potential thermal mechanical form kinetic calorie joules smaller or less resistance multiplies wheel and axle Efficiency flow insulators energy Thermal energy energy radiation convection conduction conduction waves energy transverse, compressional transverse Seismic rarefaction crests wavelength wavelength normal diffraction trough 124. ANS: natural frequency