Physics Practice Questions Heat Transfer and Change of Phase

considerably colder

17. If air were a better conductor than it is, at nighttime the earth would be a. considerably colder. b. considerably warmer. c. not appreciably different in temperature.

the paper cup cannot become appreciably hotter than the water it contains

18. A water-filled paper cup held in a flame will not catch fire. This is because a. the inside of the paper is wet. b. water is an excellent conductor of heat. c. paper is a poor conductor of heat. d. the paper cup cannot become appreciably hotter than the water it contains.

can't say, because thermal energy is not temperature

19. An object will normally be a net radiator of energy when its thermal energy is a. more than that of its surroundings. b. less than that of its surroundings. c. can't say, because thermal energy is not temperature

looseness of outer electrons in metal atoms

2. Metals are both good heat conductors and also good electrical conductors because of the a. similarity between thermal and electrical conductive properties. b. looseness of outer electrons in metal atoms. c. relatively high densities of metals. d. high elasticity of metals. e. ability of metals to transfer energy easily.

both of these

20. Newton's law of cooling applies to objects that are a. cooling. b. heating. c. both of these d. none of these

low thermal conductivity of the coals

21. One of the main reasons people can walk barefoot on red-hot coals of wood without burning their feet has to do with a. low temperature of the coals. b. low thermal conductivity of the coals. c. mind over matter techniques.

radiation

22. The silver coating on the glass surfaces of a Thermos bottle reduces energy that is transferred a. conduction. b. convection. c. radiation. d. friction. e. none of these

cools

23. If a volume of air is warmed, it expands. If a volume of air expands, it a. warms. b. cools. c. neither warms nor cools.

increases

24. When a volume of air is compressed, its temperature a. increases. b. decreases. c. neither increases nor decreases.

less than its surroundings

25. If a poor absorber of radiation were a good emitter, its temperature would be a. less than its surroundings. b. more than its surroundings. c. the same as its surroundings.

good emitter of radiation

26. A good absorber of radiation is a a. good emitter of radiation. b. poor emitter of radiation. c. good reflector. d. none of these

poor absorber of radiation

27. A good reflector of radiation is a a. good absorber of radiation. b. good emitter of radiation. c. poor absorber of radiation. d. none of these

an igloo

28. If you were caught in freezing weather with only a candle for heat, you would be warmer in a. an igloo. b. a tent. c. a wooden house. d. a car.

stay the same

29. If molecules in a sample gas moved so they completely missed each other, the gas's temperature would a. increase. b. decrease. c. stay the same.

poor insulator

3. A good heat conductor is a a. poor insulator. b. good insulator. c. neither a poor nor a good insulator

hydrogen

30. In a mixture of hydrogen gas, oxygen gas, and nitrogen gas, the molecules with the greatest average speed are those of a. hydrogen. b. oxygen. c. nitrogen. d. All will have the same average speed at the same temperature.

has a higher temperature than the earth

31 . The reason the Sun's radiant energy is of shorter wavelengths than the earth's is because the Sun a. has much more thermal energy. b. has a higher temperature than the earth. c. is an energy source while the earth is primarily an energy receiver. d. all of these e. none of these

all of these

1 . A substance can absorb heat energy by the process of a. conduction. b. convection. c. radiation. d. all of these

both of these

10. If an object radiates more energy than it absorbs, its a. thermal energy decreases. b. temperature decreases. c. both of these d. neither of these

absorber of radiant energy

11 . The pupil of your eye is a net a. absorber of radiant energy. b. emitter of radiant energy.

black pot

12. Hot water will cool to room temperature faster in a a. black pot. b. silver pot. c. depends more on the size of the pots than their color

black pot

13. Cold water will warm to room temperature faster in a a. black pot. b. silver pot. c. depends more on the size of the pots than their color.

higher than its surroundings

14. An object will normally be a net radiator of energy when its temperature is a. higher than its surroundings. b. lower than its surroundings. c. neither of these

supports this common knowledge

15. It is commonly thought that a can of beverage will cool faster in the coldest part of a refrigerator. Knowledge of Newton's law of cooling a. supports this common knowledge. b. shows this common knowledge is false.

presently exists

16. The technology for orbiting solar power plants a. awaits the next century. b. presently exists.

kinetic energy, but more speed

32. Hydrogen and oxygen molecules in a sample gas have the same temperature. This means the hydrogen molecules, on average, have the same a. speed and the same kinetic energy. b. speed, but more kinetic energy. c. speed, but less kinetic energy. d. kinetic energy, but more speed. e. kinetic energy, but less speed.

right away

33. Suppose you are served coffee at a restaurant before you are ready to drink it. In order for it to be the hottest when you are ready for it, you should add cream a. right away. b. at any time. c. when you are ready to drink the coffee.

off

34. Suppose you want to save energy and you're going to leave your warm house for a half hour on a cold day. You should turn the thermostat a. down a little. b. up a little. c. off. d. to room temperature.

off altogether

35. Suppose you want to save energy and you're going to leave your cool house for a half hour on a hot day. You should turn the temperature setting on the air conditioner a. down a little. b. up a little. c. off altogether. d. to room temperature.

radiation

36. The planet Earth loses heat mainly by a. conduction. b. convection. c. radiation. d. all of these

less than twice

37. Double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by a. less than twice. b. twice. c. more than twice.

a great variety of speeds

38. The molecules in a room-temperature glass of water jostle around at a. a great variety of speeds. b. much the same rates of speed.

warming process

39. Evaporation is a cooling process and condensation is a a. warming process. b. cooling process also. c. neither a warming nor cooling process

is a better insulator than tile

4. Your. feet feel warmer on a rug than on a tile floor because the rug a. is usually warmer than tile. b. is a better insulator than tile. c. for the same mass has more thermal energy than tile. d. all of these e. none of these

the more energetic molecules are able to escape the liquid

40. Evaporation is a cooling process because a. heat is radiated during the process. b. of conduction and convection. c. the more energetic molecules are able to escape the liquid. d. the temperature of the remaining liquid decreases. e. none of these

water left behind cools

41 . To say that evaporation is a cooling process is to say that the a. water left behind cools. b. surrounding air cools.

to help evaporation occur in its mouth and bronchial tract

42. A hot dog pants a. to help evaporation occur in its mouth and bronchial tract. b. to bring more oxygen into its lungs. c. for no particular reason-some things just happen. d. to impress dogs of the opposite sex.

both of these

43. Steam burns are more damaging than burns caused by boiling water because steam a. gives up additional energy when it condenses. b. has more energy per kilogram than boiling water. c. both of these d. neither of these

condensing on our bodies

44. We feel uncomfortably warm on a muggy day because water molecules are a. evaporating from our moist bodies. b. condensing on our bodies. c. preventing the evaporation from our moist bodies.

transfer some of their kinetic energies to us

45. We are warmed by condensation because water molecules in the air that strike our bodies a. transfer some of their kinetic energies to us. b. gain kinetic energy as they change state. c. form an insulating layer on our bodies.

stays the same

46. When heat is added to boiling water, the water temperature a. increases. b. decreases. c. stays the same.

prevent boiling

47. Increased air pressure on the surface of hot water tends to a. prevent boiling. b. promote boiling. c. neither

a lower temperature than at sea level

48. In the mountains, water boils at a. a higher temperature than at sea level. b. a lower temperature than at sea level. c. the same temperature as at sea level.

faster

49. Compared to a glass of ice water with ice in it, a glass of plain ice-cold water without ice on a warm day will warm up a. faster. b. slower. c. in the same amount of time.

fluids

5. Energy transfer by convection is primarily restricted to a. solids. b. liquids. c. gases. d. fluids. e. none of these

less than at sea level

50. When bringing water to a boil in the mountains, the time needed to reach the boiling point is a. less than at sea level. b. more than at sea level. c. the same as at sea level.

higher temperature

51 . Food in a pressure cooker is cooked faster because of the a. higher temperature. b. greater rate of bubble formation in the water. c. increased thermal energy in the water. d. all of these e. none of these

neither of these

52. Food cooked in boiling water in the mountains cooks slower than when cooked at sea level. If the temperature under the pot is increased, the food will cook a. faster. b. slower. c. neither of these

boil the eggs for a longer time

53. If you want to cook eggs by boiling them while in the mountains, then compared to sea level cooking, you should a. use a hotter flame. b. boil the eggs for a shorter time. c. boil the eggs for a longer time. d. none of these

coffee percolator

54. The operation of a geyser, such as Old Faithful in Yellowstone park, is most like the operation of a a. vacuum bottle. b. canteen. c. coffee percolator. d. teakettle. e. vat of molten lead.

raises the boiling point of water

55. An inventor discovers a harmless and tasteless salt, which, when added to water changes its boiling point. The market value for this salt will be best if the salt a. lowers the boiling point of water. b. raises the boiling point of water. c. either raises or lowers the boiling point, as the food would be cooked either way.

condensation of steam inside

56. Consider a steaming aluminum soda-pop can that contains a small amount of boiling water. When it is quickly inverted into a bath of cooler water, the can is dramatically crushed by atmospheric pressure. This occurs because the pressure inside the can is rapidly reduced by a. contact with the relatively cool water. b. sudden slowing of the air and steam molecules inside. c. condensation of steam inside. d. reduced thermal energy. e. rapid conduction of heat to the relatively cool water.

releases energy

57. When a gas is changed to a liquid phase, the gas a. releases energy. b. absorbs energy. c. neither releases nor absorbs energy.

absorbs energy

58. When a solid is changed to a liquid phase, the solid a. releases energy. b. absorbs energy. c. neither releases nor absorbs energy.

release energy

59. When liquids change to a solid phase, they a. absorb energy. b. release energy. c. neither absorb nor release energy.

both of these

6. Warm air rises because faster moving molecules tend to move to regions of less a. density. b. pressure. c. both of these

100 g of steam at 100°C

60. Which would burn the most? a. 100 g of water at 100°C b. 100 g of steam at 100°C c. Both would be equally damaging.

stays the same

61 . When heat is added to boiling water, water temperature a. increases. b. decreases. c. stays the same.

wet

62. Suppose you walk on red hot coals with bare feet. Providing bits of coal do not stick to your feet, it would be best if your feet are a. wet. b. dry. c. either wet or dry-it makes no difference.

50 calories

63. Increasing the temperature of 50 grams of water by 1°C requires a. 1 calorie. b. 50 calories. c. none of these

none of these

64. To melt 50 g of O°C ice requires a. 25 calories. b. 50 calories. c. 80 calories. d. none of these

more calories than is required to bring 50 g of ice at absolute zero to the boiling point

65. To turn 50 g of boiling water to steam requires a. 50 calories. b. 500 calories c. 540 calories. d. more calories than is required to bring 50 g of ice at absolute zero to the boiling point. e. none of these

removes thermal energy from inside the refrigerator

66. A refrigerator a. produces cold. b. causes thermal energy to disappear. c. removes thermal energy from inside the refrigerator. d. changes heat into cold. e. none of these

vaporizing the refrigeration liquid

67. The cooling effect inside a refrigerator is produced by a. an electric motor that converts electrical energy into thermal energy. b. compressing the refrigeration gas into a liquid. c. vaporizing the refrigeration liquid. d. proper insulation. e. none of these

crushed

68. Ice is put in a cooler in order to cool the contents. To speed up the cooling process, the ice can be a. wrapped in newspaper. b. drained of ice water periodically. c. kept out of contact with the food. d. crushed. e. kept in circulating air currents provided by a small fire under one end of the cooler.

the condensation of 1 g of steam at 100oC to 100oC water

69. Which involves the larger number of calories? a. the condensation of 1 g of steam at 100oC to 100oC water b. the change of phase of 1 g of 100oC water to 1 g of ice at absolute zero c. both involve the same number of calories

very light molecules

7. At the same temperature, which move with the greater speed in the air? a. very light molecules b. heavier molecules c. All will have equal average speeds.

8g

70. The number of grams of ice that can be melted by 1 g of 100oC steam is a. 0.125 g. b. 0.148 g. c. 6.75 g. d. 8g. e. none of these

shorter the wavelengths it radiates

8. The higher the temperature of an object, the a. longer the wavelengths it radiates. b. shorter the wavelengths it radiates.

absorb radiation relatively well

9 . Objects that radiate relatively well a. absorb radiation relatively well. b. reflect radiation relatively well. c. both of these d. neither of these