9. A figure skater with arms initially extended starts spinning on the ice at 3 rad/s. She then pulls her arms in close to her body. Which of the following results? a. a smaller rotational rate b. a greater rotational rate c. a greater angular momentum d. a smaller angular momentum

11. The Earth moves about the Sun in an elliptical orbit. As the Earth moves closer to the Sun, which of the following best describes the Earth Sun system's moment of inertia? a. decreases b. increases c. remains constant d. none of the above choices are valid

18. A bucket of water with total mass 23 kg is attached to a rope, which in turn is wound around a 0.050-m radius cylinder at the top of a well. A crank with a turning radius of 0.25 m is attached to the end of the cylinder. What minimum force directed perpendicular to the crank handle is required to raise the bucket? (Assume the rope's mass is negligible, that cylinder turns on frictionless bearings, and that g = 9.8 m/s2.) a. 45 N b. 68 N c. 90 N d. 135 N

22. A solid sphere of mass 4.0 kg and radius 0.12 m is at rest at the top of a ramp inclined 15°. It rolls to the bottom without slipping. The upper end of the ramp is 1.2 m higher than the lower end. Find the sphere's total kinetic energy when it reaches the bottom. a. 70 J b. 47 J c. 18 J d. 8.8 J

27. An ice skater spins at 2.5 rev/s when his arms are extended. He draws his arms in and spins at 6.0 rev/s. By what factor does his moment of inertia change in the process? a. 2.4 b. 1.0 c. 0.42 d. 0.12

28. A figure skater on ice with arms extended, spins at a rate of 2.5 rev/s. After he draws his arms in, he spins at 6.0 rev/s. By what factor does the skater's kinetic energy change when he draws his arms in? a. 2.4 b. 1.0 c. 0.42 d. 0.12

30. A turntable has a moment of inertia of 3.00 ´ 10-2 kg×m2 and spins freely on a frictionless bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.100 m from the center. By what factor does the angular momentum of the system change after the putty is dropped onto the turntable? a. 1.22 b. 1.00 c. 0.820 d. 1.50

39. A cylinder (I = MR2/2) is rolling along the ground at 7.0 m/s. It comes to a hill and starts going up. Assuming no losses to friction, how high does it get before it stops? a. 1.2 m b. 3.7 m c. 4.2 m d. 5.9 m

41. The Earth's gravity exerts no torque on a satellite orbiting the Earth in an elliptical orbit. Compare the motion at the point nearest the Earth (perigee) to the motion at the point farthest from the Earth (apogee). At these two points: a. the tangential velocities are the same. b. the angular velocities are the same. c. the angular momentum is the same. d. the kinetic energies are the same.

46. A meter stick is hinged at its lower end and allowed to fall from a vertical position. If its moment of inertia is ML2/3, with what angular speed does it hit the table? a. 5.42 rad/s b. 2.71 rad/s c. 1.22 rad/s d. 0.61 rad/s

48. An astronaut is on a 100-m lifeline outside a spaceship, circling the ship with an angular speed of 0.100 rad/s. How far inward can she be pulled before the centripetal acceleration reaches 5g = 49 m/s2? a. 10.1 m b. 50.0 m c. 72.7 m d. 89.9 m

50. A uniform bridge span weighs 50.0 ´ 103 N and is 40.0 m long. An automobile weighing 15.0 ´ 103 N is parked with its center of gravity located 12.0 m from the right pier. What upward support force does the left pier provide? a. 29.5 ´ 103 N b. 35.5 ´ 103 N c. 65.0 ´ 103 N d. 32.5 ´ 103 N

53. A 100-N uniform ladder, 8.0 m long, rests against a smooth vertical wall. The coefficient of static friction between ladder and floor is 0.40. What minimum angle can the ladder make with the floor before it slips? a. 22° b. 51° c. 18° d. 42°

62. A solid sphere rolls down an incline of height 3 m after starting from rest. In order to calculate its speed at the bottom of the incline, one needs to know a. the mass of the sphere. b. the radius of the sphere. c. the mass and the radius of the sphere. d. no more than is given in the problem.

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17. A ping-pong ball has an average density of 0.0840 g/cm3 and a diameter of 3.80 cm. What force would be required to keep the ball completely submerged under water? a. 1.000 N b. 0.788 N c. 0.516 N d. 0.258 N

23. If the column of mercury in a barometer stands at 72.6 cm, what is the atmospheric pressure? (The density of mercury is 13.6 ´ 103 kg/m3 and g = 9.80 m/s2) a. 0.968 ´ 105 N/m2 b. 1.03 ´ 105 N/m2 c. 0.925 ´ 105 N/m2 d. 1.07 ´ 105 N/m2

28. As ice floats in water, about 10% of the ice floats above the surface of the water. If we float some ice in a glass of water, what will happen to the water level as the ice melts? a. The water level will rise 10% of the volume of the ice that melts. b. The water level will rise, but not as much as the 10% indicated in answer A. c. The water level will remain unchanged. d. The water level will become lower.

31. A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the: a. weight of the stone. b. weight of the water displaced. c. sum of the weight of the stone and the weight of the displaced water. d. difference between the weight of the stone and the weight of the displaced water.

32. The pressure inside a commercial airliner is maintained at 1.00 atm (105 Pa). What is the net outward force exerted on a 1.0 m ´ 2.0 m cabin door if the outside pressure is 0.30 atm? a. 140 N b. 1 400 N c. 14 000 N d. 140 000 N

38. A blimp is filled with 400 m3 of helium. How big a payload can the balloon lift? (The density of air is 1.29 kg/m3; the density of helium is 0.18 kg/m3.) a. 111 kg b. 129 kg c. 215 kg d. 444 kg

49. A hole is poked through the metal side of a drum holding water. The hole is 18 cm below the water surface. What is the initial speed of outflow? a. 1.9 m/s b. 2.96 m/s c. 3.2 m/s d. 3.5 m/s

52. A fountain sends water to a height of 100 m. What must be the pressurization (above atmospheric) of the underground water system? (1 atm = 105 N/m2) a. 1 atm b. 4.2 atm c. 7.2 atm d. 9.8 atm

58. Water is sent from a fire hose at 30 m/s at an angle of 30° above the horizontal. What is the maximum height reached by the water? a. 7.5 m b. 11 m c. 15 m d. 19 m

61. How deep under the surface of a lake would the pressure be double that at the surface? (1 atm = 1.01 × 105 Pa) a. 1.00 m b. 9.80 m c. 10.3 m d. 32.2 m

63. A heavily loaded boat is floating in a pond. The boat sinks because of a leak. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed to reach a conclusion.

64. A heavily loaded boat is floating in a pond. The boat starts to sink because of a leak but quick action plugging the leak stops the boat from going under although it is now deeper in the water. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed to reach a conclusion.

65. A block of wood has specific gravity 0.80. When placed in water, what percent of the volume of the wood is above the surface? a. 0, the block sinks. b. 20% c. 25% d. 80%

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5. Dmitri places one end of a copper rod in a heat reservoir and the other end in a heat sink. By what factor is the rate of heat flow changed when the temperature difference between the reservoir and sink is tripled? a. 0.33 b. 1/9 c. 3.0 d. 9.0

8. The use of fiberglass insulation in the outer walls of a building is intended to minimize heat transfer through what process? a. conduction b. radiation c. convection d. vaporization

10. Heat flow occurs between two bodies in thermal contact when they differ in what property? a. mass b. specific heat c. density d. temperature

14. How does the heat energy from the sun reach us through the vacuum of space? a. conduction b. radiation c. convection d. none of the above choices are valid

20. An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended into heat for warming water. What minimum power must be generated if 300 g water (enough for 1 cup of coffee) is to be heated in 10 min from 20°C to 95°C? (1 cal = 4.186 J, the specific heat of water is 4 186 J/kg×°C) a. 9 400 W b. 590 W c. 160 W d. 31 W

24. A windowpane is half a centimeter thick and has an area of 1.0 m2. The temperature difference between the inside and outside surfaces of the pane is 15 C°. What is the rate of heat flow through this window? (Thermal conductivity for glass is 0.84 J/s×m×°C.) a. 50 000 J/s b. 2 500 J/s c. 1 300 J/s d. 630 J/s

25. A 2.0-m2 Thermopane window is constructed, using two layers of glass 4.0 mm thick, separated by an air space of 5.0 mm. If the temperature difference is 20 C° from the inside of the house to the outside air, what is the rate of heat flow through this window? (Thermal conductivity for glass is 0.84 J/s×m×°C and for air 0.023 4 J/s×m×°C.) a. 7 700 W b. 1 900 W c. 547 W d. 180 W

28. A 0.2-kg aluminum plate, initially at 20°C, slides down a 15-m-long surface, inclined at a 30° angle to the horizontal. The force of kinetic friction exactly balances the component of gravity down the plane so that the plate, once started, glides down at constant velocity. If 90% of the mechanical energy of the system is absorbed by the aluminum, what is its temperature increase at the bottom of the incline? (Specific heat for aluminum is 900 J/kg×°C.) a. 0.16 C° b. 0.07 C° c. 0.04 C° d. 0.03 C°

30. The filament temperature of a light bulb is 2 000 K when the bulb delivers 40 W of power. If its emissivity remains constant, what power is delivered when the filament temperature is 2 500 K? a. 105 W b. 62 W c. 98 W d. 50 W

39. As I use sandpaper on some rusty metal, the sandpaper gets hot because: a. Heat is flowing from the sandpaper into the metal. b. Heat is flowing from the metal into the sandpaper. c. Friction is creating the heat. d. Heat is flowing from my hand into the sandpaper.

60. Which of the following statements is true? a. A hot object contains a lot of heat. b. A cold object contains only a little heat. c. Objects do not contain heat. d. Statements a and b are true.

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4. A heat engine exhausts 3 000 J of heat while performing 1 500 J of useful work. What is the efficiency of the engine? a. 15% b. 33% c. 50% d. 60%

15. According to the second law of thermodynamics, which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle? a. must be completely converted to work b. equals the entropy increase c. converted completely into internal energy d. cannot be completely converted to work

16. The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following? a. hot reservoir temperature only b. cold reservoir temperature only c. both hot and cold reservoir temperatures d. None of the above choices are valid.

24. A heat engine receives 6 000 J of heat from its combustion process and loses 4 000 J through the exhaust and friction. What is its efficiency? a. 33% b. 40% c. 67% d. 73%

26. A turbine takes in 1000-K steam and exhausts the steam at a temperature of 500 K. What is the maximum theoretical efficiency of this system? a. 24% b. 33% c. 50% d. 67%

30. An avalanche of ice and snow of mass 1 800 kg slides a vertical distance of 160 m down a mountainside. If the temperature of the ice, snow, mountain and surrounding air are all at 0°C, what is the change in entropy of the universe? a. 31 000 J/K b. 10 000 J/K c. 3 200 J/K d. 1 100 J/K

47. The surface of the Sun is at approximately 5 700 K and the temperature of the Earth's surface is about 290 K. What total entropy change occurs when 1 000 J of heat energy is transferred from the Sun to the Earth? a. 2.89 J/K b. 3.27 J/K c. 3.62 J/K d. 3.97 J/K