Martin Nikolo Ch. 7

(29) By what primary heat transfer mechanism does the sun warm the earth?

Radiation

(75) Steam burns are more dangerous than burns caused by boiling water because steam

both gives up more energy when it condenses, and has more energy per kilogram than boiling water

(99) What happens to water when heated from 0 degrees C to 4 C?

Density increases

(56) Objects that radiate relatively well

absorb radiation relatively well

(34) Is it possible to transfer heat from a cold reservoir to a hot reservoir?

Yes, but work will have to be done

(88) When a solid is changed to a liquid phase, the solid

absorbs energy

(79) In the mountains, water boils at

a lower temperature at sea level

(28) Convection can occur

only in liquids and gases

(90) Which would burn the most?

100 g of steam at 100 C

(93) To turn 50 g of boiling water to steam requires

27,000 calories q=mL L= 540 cal/g C

(92) To melt 50g of 0 C ice requires

4000 calories q=mL L= 80 cal/g C

(98) The number of grams of ice that can be melted by 1 g of 100 C steam is?

8 g Q=mcdeltaT c= 1 cal/g C deltaT= 100 C Q= mL L= 540 cal/g Q= 640 cal m= Q/L m= 640/80 = 8 g

(27) If you triple the absolute temperature of an object, it will radiate energy

81 times faster

(30) By what primary heat transfer mechanism does one end of a spoon become hot when the other end is placed in boiling water?

Conduction

(18) If your hands are being warmed by holding them above a flame, then the primary form of heat transfer is which process?

Convection

(25) A chunk of ice (T= -20 C) is added to a thermally insulated container of cold water (T=0 C). What happens in the container?

Some of the water freezes and the chunk of ice gets larger

(32) Saturation occurs in air when the

air contains as many water molecules as it can contain at a given temperature

(68) If you were caught in freezing weather with only a candle for heat, you would be warmer in

an igloo

(57) Hot water will cool to room temperature faster in a

black pot

(58) Cold water will warm to room temperature faster in a

black pot

(84) If you want to cook eggs by boiling them while in the mountains, then compared to sea level cooking, you should

boil the eggs for a longer time

(61) An object will normally be a net radiator of energy when its thermal energy is

can't say because thermal energy is not temperature

(86) 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

condensation of steam inside

(13) The space between the inner walls of a thermos bottle is evacuated to minimize heat transfer by

conduction and convection

(50) A substance can absorb heat energy by the process(es) of

conduction, convection, and radiation

(59) If air were a better conductor than it is, at nightime the earth would be

considerably colder

(96) Ice is put in a cooler in order to cool the contents. To speed up the cooling process, the ice can be

crushed

(33) When water freezes, the entropy of the water

decreases

(55) Warm air rises because faster moving molecules tend to move to regions of less

density and pressure

(35) The second law of thermodynamics leads us to conclude that

disorder in the universe is increasing with the passage of time

(63) If a volume of air is warmed, it

expands

(80) 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

faster

(54) Energy transfer by convection is primarily restricted to

fluids

(66) A good absorber of radiation is a

good emitter of radiation

(31) When a vapor condenses

heat energy leaves a substance

(82) Food in a pressure cooker is cooked faster because of the

higher temperature

(64) When a volume of air is compressed, its temperature

increases

(53) Your feet feel warmer on a rug than on a tile floor because the rug

is a better insulator than tile

(70) Hydrogen and oxygen molecules in a sample gas have the same temperature. This means the hydrogen molecules, on average, have the same

kinetic energy, but more speed

(81) When bringing water to a boil in the mountains, the time needed to reach the boiling point is

less than at sea level

(65) If a poor absorber of radiation were a good emitter, its temperature would be

less than its surroundings

(73) Double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by

less than twice

(51) Metals are both good heat conductors and also good electrical conductors because of the

looseness of outer electrons in metal atoms

(83) 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

neither faster nor slower

(67) A good reflector of radiation is a

poor absorber of radiation

(52) A good heat conductor is a

poor insulator

(78) Increased air pressure on the surface of hot water tends to

prevent boiling

(4) If holding hands to one side of a flame, the predominant form of heat transfer is what process?

radiation

(62) The silver coating on the glass surfaces of a Thermos bottle reduces energy that is transferred by

radiation

(72) The planet Earth loses heat mainly by

radiation

(85) 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

raises the boiling point of water

(89) When liquids change to a solid phase, they

release energy

(87) When a gas is changed to a liquid phase, the gas

releases energy

(94) A refrigerator

removes thermal energy from inside the refrigerator.

(7) The primary reason why a sandy beach gets so hot on a sunny day is because

sand has a small specific heat

(19) Sea breezes on a beach are attributed to a difference between land and water with respect to what property?

specific heat

(69) If molecules in a sample gas moved so they completely missed each other, the gas's temperature would

stay the same

(77) When heat is added to boiling water, the water temperature

stays the same

(97) Which involves the large number of calories?

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

(74) Evaporation is a cooling process because

the more energetic molecules are able to escape the liquid

(60) A water-filled paper cup held in flame will not catch fire. This is because

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

(76) We are warmed by condensation because water molecules in the air that strike our bodies

transfer some of their kinetic energies to us

(95) The cooling effect inside a refrigerator is produced by

vaporizing the refrigeration liquid

(91) 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

wet

(71) 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

when you are ready to drink the coffee