Physics ch 16 textbook

good insulator

= (poor conductor)

Atmospheric gases

? (mainly water vapor and carbon dioxide) absorb and re-emit much of this long-wavelength terrestrial radiation back to Earth

good/black

? absorber appears dark and a perfect absorber reflects no radiant energy and appears completely ?

Convection

? can occur in all fluids, whether liquids or gases. Whether we heat water in a pan or heat air in a room, the process is the same As the fluid is heated from below, the molecules at the bottom begin to move faster, spreading apart more, becoming less dense, and being buoyed upward (Archimedes' principle).

Convection

? occurs wherever fluids are subjected to temperature differences. It produces clouds in the sky and contributes to ocean currents in deep ocean waters

Convection currents

? stirring the atmosphere 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

Terrestrial radiation

? that cannot escape Earth's atmosphere keeps Earth from getting too cold. This greenhouse effect is very nice because Earth would be a frigid

Low-frequency/ high-frequency

? vibrations produce long-wavelength waves, and ? vibrations produce short ones.

reflects

A good absorber of radiant energy ? very little radiant energy, including visible light

A home becomes colder because heat flows out. Homes are insulated with rock wool to prevent heat loss rather than to prevent cold from entering. It is important to note that no insulator can totally prevent heat loss. An insulator merely reduces the rate at which heat penetrates. Even the best-insulated warm homes in winter will gradually cool. Insulation slows heat transfer.

A home becomes colder because heat flows out. Homes are insulated with rock wool to prevent heat loss rather than to prevent cold from entering. It is important to note that no insulator can totally prevent heat loss. An insulator merely reduces the rate at which heat penetrates. Even the best-insulated warm homes in winter will gradually cool. Insulation slows heat transfer.

convection

A means of heat, transfer by movement of the heated subs in itself, such as by currents in a fluid

poor

Air is a very ? conductor

infrared /visible

Air is transparent to both ? (long) wavelengths and ? (short) wavelengths, unless the air contains excess water vapor and carbon dioxide, in which case it is opaque to infrared.

radiant energy

All substances at any temperature above absolute zero emit ?

radiates /cooler

An object left out in the open at night ?energy into space and, because space itself is extremely cold, it receives very little energy in return. Thus, it gives out more energy than it receives and becomes ?

At a temperature of about an object begins to emit the longest wavelength radiation we can see, red light. As its temperature is raised, it becomes "red hot," then appears yellowish, and, at around , where it emits light strongly in all visible wavelengths, it is "white hot." A blue star is hotter than a white star, which, in turn, is hotter than a red star. If a particular blue star emitted light of twice the peak frequency of light from a certain red star, the blue star would have twice the surface temperature of the red star

At a temperature of about an object begins to emit the longest wavelength radiation we can see, red light. As its temperature is raised, it becomes "red hot," then appears yellowish, and, at around , where it emits light strongly in all visible wavelengths, it is "white hot." A blue star is hotter than a white star, which, in turn, is hotter than a red star. If a particular blue star emitted light of twice the peak frequency of light from a certain red star, the blue star would have twice the surface temperature of the red star

electromagnetic spectrum

Because the surface of the Sun has a high temperature (by earthly standards), it emits radiant energy at a high frequency—much of it in the visible portion of the ?

insulator

Because wood is a good ? (poor conductor) of heat, it is used in the handles of cookware

solar radiation

Bodies that radiate more energy than they receive become cooler. This happens at night when there is no ?

Both the Sun and Earth emit the same kind of radiant energy. The Sun's glow is visible to the eye; Earth's glow consists of longer wavelengths and isn't visible to the eye.

Both the Sun and Earth emit the same kind of radiant energy. The Sun's glow is visible to the eye; Earth's glow consists of longer wavelengths and isn't visible to the eye.

good reflector

Clean snow is a ? and therefore does not melt rapidly in sunlight. If the snow is dirty, it absorbs radiant energy from the Sun and melts faster

air temperature.

Convection currents occur in the atmosphere and affect ? When a parcel of air near the ground is warmed, it expands, becomes less dense, and is buoyed upward

Convection currents occur in the atmosphere and affect air temperature. When a parcel of air near the ground is warmed, it expands, becomes less dense, and is buoyed upward. Hence, warmed air rises. The rising air is then actually cooled as it expands further, doing work on the lower-pressure air that it encounters at higher altitude. So the energy acquired initially by the parcel of air, perhaps from solar radiation, is more than offset by the energy it loses in doing work as it expands on its way up. The result: Air temperature is lower at higher altitude

Convection currents occur in the atmosphere and affect air temperature. When a parcel of air near the ground is warmed, it expands, becomes less dense, and is buoyed upward. Hence, warmed air rises. The rising air is then actually cooled as it expands further, doing work on the lower-pressure air that it encounters at higher altitude. So the energy acquired initially by the parcel of air, perhaps from solar radiation, is more than offset by the energy it loses in doing work as it expands on its way up. The result: Air temperature is lower at higher altitude

convection currents

Denser, cooler fluid moves in to take the place of the warmer fluid at the bottom. In this way, ? keep the fluid stirred up as it heats—warmer fluid moving away from the heat source and cooler fluid moving toward the heat source.

An insulator slows heat transfer.

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

Earth itself exchanges radiation with its surroundings. The Sun is a dominant part of Earth's surroundings during the day. The sunlit half of Earth absorbs more radiant energy than it emits. At night, if the air is relatively transparent with no cloud cover, Earth radiates more energy to deep space than it receives in return

Earth itself exchanges radiation with its surroundings. The Sun is a dominant part of Earth's surroundings during the day. The sunlit half of Earth absorbs more radiant energy than it emits. At night, if the air is relatively transparent with no cloud cover, Earth radiates more energy to deep space than it receives in return

solar power

Energy per unit time derive from the sun

Conduction

Energy transfer from particle to particle within certain materials or from what material to another when the two are indirect contact

absorbs and emits

Every surface, hot or cold, both ? radiant energy.

Glass is transparent to short-wavelength radiation but opaque to long-wavelength radiation. Reradiated energy from the plant (or anything else in the greenhouse) has a long wavelength because the plant has a relatively low temperature.

Glass is transparent to short-wavelength radiation but opaque to long-wavelength radiation. Reradiated energy from the plant (or anything else in the greenhouse) has a long wavelength because the plant has a relatively low temperature.

good

Good emitters of radiant energy are also ? absorbers; poor emitters are poor absorbers

poor

Good emitters of radiant energy are also good absorbers; poor emitters are ?absorbers

Heat transfer by conduction through the vacuum is impossible. Some heat escapes by conduction through the glass and stopper, but this is a slow process because glass, plastic, and cork are poor conductors. The vacuum has no fluid to convect, so there is no heat loss through the walls by convection. Heat loss by radiation is reduced by the silvered surfaces of the walls, which reflect heat wavelengths back into the bottle.

Heat transfer by conduction through the vacuum is impossible. Some heat escapes by conduction through the glass and stopper, but this is a slow process because glass, plastic, and cork are poor conductors. The vacuum has no fluid to convect, so there is no heat loss through the walls by convection. Heat loss by radiation is reduced by the silvered surfaces of the walls, which reflect heat wavelengths back into the bottle.

short /long

High-temperature objects radiate ?wavelengths; low-temperature objects radiate ? wavelengths

conducts

How well a metal fork or any solid object ?heat depends on the bonding within its atomic or molecular structure

visible light

If an object is hot enough, some of the radiant energy it emits is in the range of ?

drops

If it emits more than it absorbs, it is a net emitter and its temperature ?

net absorber and become warmer.

If its surface is colder than its surroundings, it will be a ?

more/rises.

If the surface absorbs ? energy than it emits, it is a net absorber and its temperature ?

net emitter and will cool.

If the surface is hotter than its surroundings, it will be a ?

Convection

In Earth's interior, the ?of semimolten material is the likely cause of sliding tectonic plates, which produce events such as earthquakes and volcanic eruptions.? also plays a large role in the Sun, producing a relatively steady overall brightness. Solar ? also accounts for solar flares

Convection currents

In the daytime, the shore warms more easily than the water. Air over the shore is pushed up (we say it rises) by cooler air that comes in from above the water to take its place. The result is a sea breeze. At night, the process reverses: The shore cools off more quickly than the water, and then the warmer air is over the sea

radiant energy

It includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays

Left to themselves, objects hotter than their surroundings eventually cool to match the surrounding temperature. The rate of cooling depends on how much hotter the object is than its surroundings.

Left to themselves, objects hotter than their surroundings eventually cool to match the surrounding temperature. The rate of cooling depends on how much hotter the object is than its surroundings.

radiation

Light energy from the Sun passes through space and then through Earth's atmosphere and warms Earth's surface. This energy does not pass through the atmosphere by conduction because air is a poor conductor. Nor does it pass through by convection because convection begins only after Earth is warmed

conductors

Metals have the "loosest" outer electrons, which are free to carry energy by collisions throughout the metal. That is why metals are excellent ? of heat and electricity

photovoltaic

More and more rooftops are fitted with ? cells that convert sunlight directly to electricity

poor /insulators

Most liquids and gases are? conductors. ?conductors that impede the transfer of heat are called ?

infrared

Objects with everyday temperatures emit mostly low-frequency waves that are invisible to the human eye

good insulators

Other porous substances such as fiberglass are likewise ? because of their many small air spaces. Be glad that air is a poor conductor; if it were not, you'd feel quite chilly on a

electromagnetic waves

Radiant energy is in the form of ?

newtons law of cooling-applies to warming

Rate of cooling of an object, weather by conduction, convection, or radiation, is proportional to the temperature difference between the object and its surroundings

radiation

Since conduction and convection depend on molecular motion, we therefore know that neither process is possible in the empty space between our atmosphere and the Sun. We can see that energy must be transmitted by some other means—

(a good insulator)

Snow is a poor conductor? —about the same as dry wood

So energy from the Sun gets into the car's interior, where, except for reflection, it is absorbed. The interior of the car warms up. The car's interior radiates its own wavelengths, but, since it is not as hot as the Sun, the wavelengths are longer. The reradiated long wavelengths encounter glass that isn't transparent to them. So the reradiated energy remains in the car, which makes the car's interior even warmer

So energy from the Sun gets into the car's interior, where, except for reflection, it is absorbed. The interior of the car warms up. The car's interior radiates its own wavelengths, but, since it is not as hot as the Sun, the wavelengths are longer. The reradiated long wavelengths encounter glass that isn't transparent to them. So the reradiated energy remains in the car, which makes the car's interior even warmer

conduct

Solids composed of atoms that have one or more "loose" outer electrons ? heat (and electricity) well

electrons

Solids composed of atoms that have one or more "loose" outer? conduct heat (and electricity) well

good/air spaces

The ? insulating properties of materials such as wool, fur, and feathers are largely due to the ? they contain.

nuclear reactions/terrestrial radiation

The Sun's radiant energy stems from ? in its deep interior. Likewise, nuclear reactions in Earth's interior warm Earth Much of this internal energy conducts to the surface to become ?

The peak frequency of the radiant energy is directly proportional to the absolute (Kelvin) temperature T of the emitter

The peak frequency of the radiant energy is directly proportional to the absolute (Kelvin) temperature T of the emitter

proportional

The rate of cooling of an object—whether by conduction, by convection, or by radiation—is approximately ? to the temperature difference between the object and its surroundings

transparent

The same effect occurs in Earth's atmosphere, which is ? to solar radiation. The surface of Earth absorbs this energy and reradiates part of this as longer-wavelength terrestrial radiation

infrared waves—

The surface of Earth, by comparison, is relatively cool, and so the radiant energy it emits consists of frequencies lower than those of visible light. The radiation emitted by Earth is in the form of ? below our threshold of sight

radiant energy

The surface of any material, hot or cold, both absorbs and emits ?

The tile floor feels colder than the wood floor, even though both floor materials are at the same temperature. This is because tile is a better conductor of heat than wood, and so heat is more readily conducted out of the foot touching the tile.

The tile floor feels colder than the wood floor, even though both floor materials are at the same temperature. This is because tile is a better conductor of heat than wood, and so heat is more readily conducted out of the foot touching the tile.

materials such as wood, straw, and grass are poor conductors and little heat is conducted into them from the ground

These insulating materials are net radiators and get colder than the air. It is common for frost to form on these kinds of materials even when the temperature of the air does not go down to freezing

convection

Unlike conduction (in which heat is transferred by successive collisions of electrons and atoms), ? involves the motion of "blobs" of matter—the overall movement of molecules of a fluid.

greenhouse effect

Warming caused by short, wave length, radiant energy from the sun. That easily enters the atmosphere and is absorbed by earth but when radiated at longer, wavelengths cannot easily escape earths atmosphere.

heat radiation

When the higher-frequency infrared waves are absorbed by your skin, as when you stand beside a hot stove, you feel the sensation of heat. So it is common to refer to infrared radiation as

temperature

Whether a surface plays the role of net emitter or net absorber depends on whether its ? is above or below that of its surroundings

good

Wool, wood, straw, paper, cork, and Styrofoam are ? insulators of heat, Unlike the electrons in metals, the outer electrons in the atoms of these insulators are firmly attached.

You will find that the black container cools faster. The blackened surface is a better emitter. Coffee or tea stays hot longer in a shiny pot than in a blackened one. The same experiment can be done in reverse. This time, fill each container with ice water and place the containers in front of a fireplace, outside on a sunny day, or wherever there is a good source of radiant energy. You'll find that the black container warms up faster. As we said, an object that emits well also absorbs well.

You will find that the black container cools faster. The blackened surface is a better emitter. Coffee or tea stays hot longer in a shiny pot than in a blackened one. The same experiment can be done in reverse. This time, fill each container with ice water and place the containers in front of a fireplace, outside on a sunny day, or wherever there is a good source of radiant energy. You'll find that the black container warms up faster. As we said, an object that emits well also absorbs well.

dark

a surface that reflects very little or no radiant energy looks ?

radiant energy

all objects emit ? over a range of frequencies

temperature

all things radiate, and the frequency and wavelength of radiation depend on the >?of the object emitting the radiation

radiation

energy transmitted by electromagnetic waves; the particles given off by radioactive atoms such as uranium

absorbing

everything is also ? energy

radiation: infrared radiation

has longer wavelengths than visible light. The longest visible wavelengths are for red light, and the shortest are for violet light

he hot Sun emits short wavelengths. The cool Earth emits long wavelengths. Water vapor, carbon dioxide, and other greenhouse gases in the atmosphere retain heat that would otherwise be radiated from Earth to space.

he hot Sun emits short wavelengths. The cool Earth emits long wavelengths. Water vapor, carbon dioxide, and other greenhouse gases in the atmosphere retain heat that would otherwise be radiated from Earth to space.

solar constant

input of energy

object is a good conductor of heat—such as metal, stone, or concrete—heat conducts from the ground, which somewhat stabilizes its temperature. On the other hand, materials such as wood, straw, and grass are poor conductors and little heat is conducted into them from the ground.

object is a good conductor of heat—such as metal, stone, or concrete—heat conducts from the ground, which somewhat stabilizes its temperature. On the other hand, materials such as wood, straw, and grass are poor conductors and little heat is conducted into them from the ground.

solar constant

rate at which solar energy is received from the Sun. The amount of solar energy that reaches the ground is attenuated by the atmosphere and reduced by nonperpendicular elevation angles of the Sun

short

the Sun's temperature is very high. This means the wavelengths radiated by the Sun are very ?

wavelength

transparency of things such as air and glass depends on the ? of radiation

frequency

wavelength of radiation is related to the ?of radiation

opposite

Absorption and reflection are >? processes

cooler

Bodies that radiate more energy than they receive become ?

Glass is transparent to visible-light wavelengths but is opaque to infrared wavelengths.

Glass is transparent to visible-light wavelengths but is opaque to infrared wavelengths.

absorbers

Good reflectors, are poor ?

convection

Liquids and gases transmit heat mainly by

terrestrial radiation

Radiant energy emitted by Earth is called