70 terms

# Physics Practice Questions Heat Transfer and Change of Phase

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all of these
1 . A substance can absorb heat energy by the process of
a. conduction.
b. convection.
d. all of these
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.
poor insulator
3. A good heat conductor is a
a. poor insulator.
b. good insulator.
c. neither a poor nor a good insulator
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
fluids
5. Energy transfer by convection is primarily restricted to
a. solids.
b. liquids.
c. gases.
d. fluids.
e. none of these
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
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.
8. The higher the temperature of an object, the
a. longer the wavelengths it radiates.
b. shorter the wavelengths it radiates.
9 . Objects that radiate relatively well
c. both of these
d. neither 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
11 . The pupil of your eye is a net
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.
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
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.
22. The silver coating on the glass surfaces of a Thermos bottle reduces energy that is transferred
a. conduction.
b. convection.
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.
26. A good absorber of radiation is a
c. good reflector.
d. none of these
27. A good reflector of radiation is a
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.
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
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.
36. The planet Earth loses heat mainly by
a. conduction.
b. convection.
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
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.
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.
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.
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
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