Chapter 16

Radiation

Every object above absolute zero radiates electromagnetic waves. Long waves are radio waves Short waves are x rays Long waves are red Short waves are violet

Because of trapped air inside, snow is a

Good insulator

In a mixture of hydrogen gas, oxygen gas, and nitrogen gas, the molecules with the greatest average speed are those of

Hydrogen

Conduction

Transfer of internal energy by electron and molecular collisions within a substance, especially a solid ▫️good conductors conduct heat quickly ▫️silver, copper, and other solid metals

Radiation

Transfer of electromagnetic energy through empty space

Convection

Transfer of heat involving only bulk motion of fluids.

Convection

Warm air expands, becomes less dense, and is buoyed upward. - It rises until its density equals that of the surrounding air. ▫️gases cool when expand and warm up when compressed

A parcel of warmed air rises due to

buoyancy

A red-hot piece of coal will cool quicker in a

cold room

Substances absorb heat energy by the process of

conduction, convection, radiation

If air were a better conductor, at nighttime Earth would be

considerably colder

A region of expanding air tends to

cool

If a volume of air is warmed, it expands and tends to

cool

If the composition of the upper atmosphere were altered to permit a greater amount of terrestrial radiation to escape, Earth would be

cooler

If a pizza radiates more energy than it absorbs, its temperature

decreases

The heat we enjoy on a sunny day is due mainly to the Sun's

enormous size

Energy transfer by convection is primarily restricted to

fluids

Solar power is used in many parts of the world for

generating electricity and heating water

A good absorber of radiation is a

good emitter of radiation

A bridge is more likely to be ice covered than the roadway on a cold day because

heat upwelling from the ground below is absent on a bridge

An apple pie will be a net emitter of energy when its temperature is

higher than its surroundings

If a pizza absorbs more energy than it emits, its temperature

increases

When a volume of air is compressed, air temperature

increases

On a cold day your feet feel warmer on a rug than on a tile floor because a rug

is a poorer conductor

When an object absorbs as much as it radiates

it remains at about the same temperature.

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

kinetic energy, but more speed

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

less than its surroundings

Metals are good conductors of both heat and electricity due to

looseness of outer electrons in metal atoms

The reason you can walk barefoot on red-hot coals of wood without burning your feet mainly involves

low conductivity of the coals

A blueberry pie will be a net absorber of energy when its temperature is

lower than its surroundings

The lower the temperature of an object, the

lower the frequency of radiation it emits and the longer the wavelengths it radiates

Which of these are good conductors?

none of the above (feathers,snow,wood)

A good reflector of radiation is a

poor absorber of radiation

A good heat conductor is

poor insulator

A Thermos bottle has double glass walls with silver coating on the glass surfaces that face each other. The silver coating reduces energy transfer by

radiation

The form of heat transfer that doesn't depend on a medium is

radiation

The planet Earth loses heat primarily by

radiation

Which body glows with electromagnetic waves? A. Sun B. Earth C. Both A and B. D. None of the above

Both A and B.

You can safely hold your fingers on both sides of a candle flame, but not directly above the flame, due mainly to

Convection

Terrestrial radiation is

Emitted by earth

Which melts faster is sunlight dirty snow or clean snow

Dirty snow

Insulation

Doesn't prevent heat flow, just slows the rate at which internal energy flows

Insulators

Poor conductors are called insulators. ▫️Have molecules with tightly held electrons in a substance vibrate in place and transfer energy slowly- these are good insulators (and poor conductors). ▫️glass, wool, wood, paper, cork, plastic foam, air. ▫️substances that trap air are good insulators

Blow on your hand with your mouth open. Then do the same with your lips puckered and you'll find

The breath from puckered lips is cooler

Wind

Winds are the result of uneven heating of the air near the ground

If there were no greenhouse effect, Earth's average temperature would likely be

a frigid -18°C.

The temperature of outer space is

about 2.7 kelvin

Objects that radiate relatively well

absorb radiation relatively well

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

all of the above

Wood is a poor conductor

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 exiting

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

an igloo

A bare roof on a warmly heated home on a snowy day indicates

an unwanted flow of heat, poor insulation, and fairly good conductivity

The higher the temperature of an object, the

shorter the wavelengths it radiates.

In practice, a good insulator

slows heat flow

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

supports this common knowledge

Sun's radiant energy is composed of shorter wavelengths than Earth's due to Sun's greater

surface temperature

Both black and white road surfaces absorb sunlight. The warmer road surface at the end of a sunny day is the

the black surface

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

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

Waves emitted by the Sun and terrestrial wave emissions are

the same except for their frequencies and wavelengths.

At the same temperature, which has greater average speed in the air?

very light molecules

Newton's law of cooling applies to objects undergoing

warming and cooling

Which is the most abundant greenhouse gas in Earth's atmosphere?

water vapor

When you touch a nail stuck in ice, energy flows from

your hand to the ice

A block of wood and a block of copper will feel neither hot nor cold to the touch when they each have

your temperature

Reflection

▫️Any surface that reflects very little radiant energy appears dark ▫️any surface that reflects a lot of radiant energy appears lighter