Chapter 16 Physics- Heat Transfer

Our atmosphere is transparent to solar radiation, but it traps the energy that causes the Greenhouse Effect. Why?

Because the solar energy absorbed by Earth is reradiated as longer-wavelength radiation

How is the speed of an air molecule affected when hit by an approaching faster-moving molecule?

Like colliding billiard balls, the molecule being hit rebounds with increased speed.

How would decreasing the percentage of greenhouse gases affect the amount of infrared radiation reflected by the atmosphere back toward Earth?

The amount of infrared radiation would decrease.

How would increasing the density of air in the atmosphere affect the amount of infrared radiation returned by the atmosphere back toward Earth?

The amount of infrared radiation would increase.

Why can a barefoot firewalker step quickly without harm on red-hot coals? Wood, even as red-hot coals, is a good conductor of heat. Wood, even as red-hot coals, is a poor conductor of heat. Bare feet are poor conductors of heat. Bare feet are good conductors of heat.

Wood, even as red-hot coals, is a poor conductor of heat.

When air rapidly expands, its temperature normally _________. increases is unaffected, but not always remains unchanged decreases

decreases

The peak frequency of radiant energy is ___________________ to the absolute temperature of the emitter

directly proportional. f is proportional to T

radiation is in the form of ____

electromagnetic waves

Thermal conduction mostly involves the motion of ___________. neutrons atoms air molecules electrons

electrons

Thermal convection is linked mostly to

fluids. Convection is the flow of heated or cooled material from one location to another. Fluids, by definition, flow.

When your foot stands on a tile floor, thermal energy always flows _________. from either your foot or the tile, depending on the temperature of the tile from the tile to your foot always upward from your foot to the tile

from either your foot or the tile, depending on the temperature of the tile

When you touch a cold piece of ice with your finger, energy flows

from your finger to the ice

loose outer electrons equals ____ firm outer electrons equals____

good conductor; poor conductor

Good emitters of radiant energy are also ____ absorbers; poor emitters are ____ absorbers.

good; poor

What type of gas absorbs and re-emits infrared radiation?

greenhouse gases

Newton's law of cooling applies to objects that undergo neither cooling nor warming only warming cooling or warming only cooling

cooling or warming

The moderate temperatures of islands throughout the world has much to do with water's

high specific heat

If a given object transfers heat quickly, then it's said to have ___ thermal conductivity. Similarly, objects with ___ thermal conductivity take longer to transfer heat.

high; low

A water-filled paper cup held in a flame will not catch fire because

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

terrestrial radiation

the radiant energy emitted by Earth. in the form of infrared waves

How would you walk on red-hot coals without getting your feet burned? Walk fast. You can either walk slowly or walk fast. Walk slowly.

walk fast

greenhouse effect

warming that results when solar radiation is trapped by the atmosphere

A region of expanding air tends to

cool

a region of expanding air tends to

cool

how does a greenhouse work

1. Sunlight streams through the glass into the greenhouse 2. Sunlight is absorbed by plants inside the greenhouse and the plants radiate the energy as thermal energy 3. The glass stops the thermal energy from escaping

The temperature at the bottom of Lake Tahoe, high in the Sierra Nevada Mountains in California, at this moment is

4 degrees C

Which will normally warm faster--a black pot of cold water or a silvered pot of cold water? Which will cool faster? A silvered pot warms faster and cools faster than a black pot. A black pot warms faster and cools faster than a silvered pot. A black pot warms faster, while a silvered pot cools faster. A silvered pot warms faster, while a black pot cools faster.

A black pot warms faster and cools faster than a silvered pot.

Why do some gardeners cover plants with a tarp at night in cold weather?

A tarp catches the thermal radiation from the cooling ground and partially re-emits it to the plants.

Does a good insulator prevent or merely slow the transfer of thermal energy?

An insulator slows heat transfer.

If the temperature of a sample of water at 4°C is slightly lowered, its volume A. remains the same. B. increases. C. decreases.

B. increases

Your feet feel warmer on a rug than on your tile floor because your rug A) is usually warmer than your tile. B) is a better insulator than your tile. C) for the same mass has more internal energy than your tile. D) all of these E) none of these

B. is a better insulator than your tile.

thermal expansion

Due to rise in temperature of a substance, molecules jiggle faster and move farther apart.

the main factor that allows firewalkers to walk barefoot on red hot coals of wood is A. All of these. B. the high conductivity of wood, even when hot. C. a determined effort and self confidence. D. a tapping of powers that go beyond physics. E. the low conductivity of wood, even when hot.

E. the low conductivity of wood, even when hot.

How do "loose" electrons affect heat conduction?

Free electrons can move through a material jostling atoms and other electrons.

How does glass act like a one-way valve for a conventional greenhouse? Does the atmosphere similarly act as a one-way valve?

Glass transmits solar radiation into the greenhouse and blocks infrared radiation from leaving the greenhouse. The same thing happens in the atmosphere.

You can hold your fingers beside the candle flame without harm, but not above the flame. Why?

Hot air travels upward by air convection. Since air is a poor conductor, very little heat travels sideways to your fingers.

Why is ice less dense than water? A. Ice crystallizes with an open structure, and the gaps that form between the water molecules in ice increase its volume. B. Water molecules slow their vibrations and move closer together when water freezes. C. When water freezes, it forms a crystal structure with less volume than liquid water. D. Some water molecules are lost when water freezes.

Ice crystallizes with an open structure, and the gaps that form between the water molecules in ice increase its volume.

If a good absorber of radiant energy were a poor emitter, how would its temperature compare with the temperature of its surroundings?

If a good absorber were not also a good emitter, there would be a net absorption of radiant energy and the temperature of the absorber would remain higher than the temperature of the surroundings. Things around us approach a common temperature only because good absorbers are, by their very nature, also good emitters.

What happens to the conductive properties of wood when it gets very hot?

It will continue to remain a good insulator.

conduction

The direct transfer of heat from one substance to another substance that it is touching.

Because all objects emit energy to their surroundings, why don't the temperatures of all objects continuously decrease?

Objects that are good emitters are equally good absorbers, so they absorb radiation as well as emit it.

How are the speeds of molecules of air affected as they separate from one another when escaping from the nozzle of a party balloon? What happens to the temperature of the air? Speeds decrease; temperature increases. Speeds stay the same; temperature stays the same. Speeds decrease; temperature decreases. Speeds increase; temperature increases.

Speeds decrease; temperature decreases.

How are the speeds of molecules of air affected when the air is compressed by the action of a tire pump? What happens to the temperature of the air? Speeds decrease; temperature decreases. Speeds increase; temperature stays constant. Speeds increase; temperature increases. Speeds increase; temperature decreases.

Speeds increase; temperature increases.

Why is one able to walk on red-hot coals without getting one's feet burned? The coals are neither very hot, nor are they good conductors of heat. The coals are not good conductors of heat. The coals are not as hot as they seem

The coals are not good conductors of heat.

Why is Millie's hand not burned when she holds it above the escape valve of the pressure cooker? The escaping hot gas is invisible. The escaping gas is cooled by condensation The escaping gas has high specific heat. The escaping gas is cooled by expansion.

The escaping gas is cooled by expansion.

How does the peak frequency of radiant energy relate to the absolute temperature of the radiating source?

The peak frequency increases as temperature increases.

Which will undergo the greater rate of cooling--a redhot poker in a warm oven or a red-hot poker in a cold room (or do both cool at the same rate)? The poker actually stays the same temperature in the oven. Both cool at the same rate. The poker in the oven cools fastest. The poker in the cold room cools fastest.

The poker in the cold room cools fastest.

newtons law of cooling

The rate of loss of heat from an object is proportional to the temperature difference between the object and its surroundings.

What is meant by the solar constant?

The solar constant is the rate of energy input per area unit from the Sun's rays at the top of the atmosphere, 1400 watts per square meter.

convection

The transfer of heat by the movement of a fluid

What does it mean to say that the greenhouse effect is like a one-way valve?

Transparent material—atmosphere for Earth and glass for the greenhouse—allows only incoming short wavelengths and blocks outgoing long wavelengths. As a result, radiant energy is trapped within the "greenhouse."

What is the main reason for the hot surface of planet Venus?

Very dense atmosphere of Venus provides a very strong greenhouse effect.

What happens to the volume of air as it rises? What happens to its temperature? Volume decreases; temperature increases. Volume increases; temperature decreases. Volume decreases; temperature decreases. Volume increases; temperature increases.

Volume increases; temperature decreases

Why can you place your hand briefly inside a hot oven without harm, but you are burned if you touch the metal sides of the oven?

When your hand is in the air of the hot oven, you're not harmed mainly because air is a poor conductor—heat doesn't travel well between the hot air and your hand. Touching the hot metal sides of the oven is another story because metal is an excellent conductor and considerable heat flows into your hand.

If you are able to grab a hot pan and pull it out by the handle without burning yourself, what kind of handle must the pan have, and why?

a wooden handle, because it is the better insulator

Any material that absorbs more than it emits is a net ____. Any material that emits more than it absorbs is a net ____. Net absorption or emission is relative to temperature of ___.

absorber; emitter; surroundings

Every equation in physics reminds us of a lesson: We can never change only one thing. When we change the composition of the atmosphere we likely also change Earth's climate. its transparency. its reflectivity. All of the above

all of the above

Glass in a florist's greenhouse acts as a one-way valve in that it

allows high-frequency waves in and blocks low-frequency waves from exiting.

Molecules in a region of expanding air collide more often with receding molecules than with ___ ones

approaching

The pupils of your eyes

are net absorbers of light and therefore appear black.

In what form does radiant energy travel? As electromagnetic waves As radioactive particles As sound waves As waves in the luminiferous aether

as electromagnetic waves

Igloos are snow houses used by the Inuit as hunting camps to protect them from the cold outside. Why are igloos warmer inside?

because ice is a good insulator

Radiation that enters the cavity has little chance of exiting because most of it is absorbed. For this reason, the opening to any cavity looks ____ to us.

black

The Thermal Expansion of Steel Is About the Same As For a) water. b) air. c) concrete. d) All of these.

concrete

A thermos bottle controls heat transfer by limiting _________. conduction, convection, and radiation conduction mainly convection mainly radiation mainly

conduction, convection, and radiation

A metal ball is just able to pass through a metal ring. When the ball is heated, however, it will not pass through the ring. What would happen if the ring, rather than the ball, were heated? Does the size of the hole increase, stay the same, or decrease?

increases

Which of these electromagnetic waves has the lowest frequency? Infrared Visible Ultraviolet Gamma rays

infrared. Low frequency vibrations produce long-wavelength waves. The longest waves listed are infrared.

which of the following normally warms up fastest when heat is applied? iron glass wood water all of these are equally true

iron

What happens to the temperature of something that radiates energy without absorbing the same amount in return? It cools. It stays the same temperature. It warms. It melts.

it cools

Which of the following would best describe the conductive properties of wood? It is a good insulator. It is neither a good conductor nor a good insulator. It is a good conductor.

it is a good insulator

A good absorber of radiant energy reflects very ______ radiant energy, including visible light.

little

Low-frequency vibrations produce ____-wavelength waves, and high-frequency vibrations produce ____ ones.

long; short

Metals are both good heat conductors and 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.

looseness of outer electrons in metal atoms.

Compared with terrestrial radiation, the radiation from the Sun has

neither a longer wavelength nor a lower frequency In accord with the relationf~T, the Sun with its enormously higher temperature has the higher frequency of radiation, which also corresponds to a long wavelength. None of the choices state this.

To save energy while you leave your warm house for several hours on a cold day, turn the thermostat

off. Energy is required to maintain a warm home because unavoidable and continuous leaking of heat. Think of keeping a glass of water full by placing it beneath a stream of running water. Less water would be used if it drained empty, then filled, than in keeping it filled all the while. Likewise with heat. You replace lost heat only once after you turn off the heat.

air is a _____ conductor of heat

poor

snow is a ____ conductor which is why igloos can keep warm, because of the ___________

poor. snow covering

Heat travels from the Sun to Earth by the process of ___________. conduction and convection, though radiation is greater radiation convection conduction

radiation

Longest electromagnetic wave; shortest?

radio waves; x-rays

Relatively speaking, do high-frequency waves have long wavelengths or short wavelengths? Name an electromagnetic wave with higher frequency than blue light. Short, ultraviolet Short, infrared Long, infrared Long, ultraviolet

short, ultraviolet

In practice, a good insulator

slows heat flow.If a substance were a perfect insulator it would stop the heat flow. But in practice, it doesn't. A good insulator slows the flow of energy.

convection currents

stir the atmosphere to produce winds. Some parts of Earth's surface absorb heat from the Sun more readily than others, and, as a result, the air near the surface is heated unevenly and convection currents form.

Ice tends to form first at the

surface of bodies of water.