Ch 3

67. For a freely falling object dropped from rest, what is the acceleration at the end of the fifth second of fall? Tenth second of fall? Defend your answers.

Ch 4

75. A 400-kg bear grasping a vertical tree slides down at constant velocity. What is the friction force that acts on the bear? Discuss how "constant velocity" is the key to your answer.

Ch 13

50. Which is more likely to hurtbeing stepped on by a 200-lb man wearing loafers or by a 100-lb woman wearing high heels? Why?

53. Why is blood pressure measured in the upper arm, at the elevation of your heart?

58. A block of aluminum with a volume of 10cm3 is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 10-cm3 block of lead. Does the lead displace more, less, or the same amount of water as the aluminum does?

59. A block of aluminum with a mass of 1 kg is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 1-kg block of lead. Does the lead displace more, less, or the same amount of water as the aluminum does?

68. Why will a block of iron float in mercury but sink in water?

79. A ship sailing from the ocean into a freshwater harbor sinks slightly deeper into the water. Does the buoyant force on the ship change? If so, does it increase or decrease?

83. When the wooden block is placed in the beaker, what happens to the scale reading? Answer the same question for an iron block.

90. If you release a ping-pong ball beneath the surface of water, it will rise to the surface. Would it do the same if it were inside a big blob of water floating weightless in an orbiting spacecraft?

95. Why can't a heavy paper clip rest on the surface of still water like a small dry paper clip without sinking?

Ch 18

69. According to the second law of thermodynamics, is the universe moving to a more ordered state or to a more disordered state?

56. According to the second law of thermodynamics, the universe tends towards a more disordered state, known as entropy increase.

Ch 19

51. If a pendulum is shortened, does its frequency increase or decrease? What about its period? How do frequency and period relate?

55. When the frequency of a wave decreases, what happens to the period? The wavelength? Use equations in your explanation.

60. What kind of motion should you impart to a stretched Slinky to provide a transverse wave? To provide a longitudinal wave?

62. Red light has a longer wavelength than violet light. Which has the greater frequency? Which has greater energy for the same intensity?

68. How many nodes, not including the endpoints, are there in a standing wave that is two wavelengths long? Three wavelengths long?

72. Why is there a Doppler effect when the source of sound is stationary and the listener is in motion? In which direction should the listener move to hear a higher frequency? A lower frequency?

75. How does the Doppler effect aid police in detecting speeding motorists?

84. Why is lightning seen before thunder is heard?

93. Astronomers find that light emitted by a particular element at one edge of a distant star has a slightly higher frequency than light from that element at the opposite edge. What do these measurements tell us about the star's motion?

Ch 28

54. Trucks often have signs on their back ends that say, "If you can't see my mirrors, I can't see you." Explain the physics here.

58. When you look at yourself in the mirror and wave your right hand, your beautiful image waves the left hand. Then why don't the feet of your image wiggle when you shake your head?

60. What must be the minimum length of a plane mirror in order for you to see a full image of yourself?

69. During a lunar eclipse, the Moon is not completely dark but is usually reddish in color, discussed in the previous chapter. Explain this in terms of the refraction of all the sunsets and sunrises around the world.

89. The law of reflection does not apply to curved mirrors. But in a limited sense, the law of reflection does apply. Discuss how this is so.

90. To reduce glare from the surroundings, the windows of some department stores, rather than being vertical, slant inward at the bottom. Discuss why this reduces glare.

95.

96. When a flashlight submerged in water shines into the air above, discuss what happens to the speed of light when passing from water into the air.

102. Two observers standing apart from one another do not see the "same" rainbow. Explain.