Chapter 7 physical Science hw

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

The gush of steam that issues from the escape valve of a pressure cooker is relatively cool

above the opening where vapor is visible.

When water changes to steam, energy is _______.

absorbed by the steam

When a solid is changed to a liquid phase, the solid

absorbs energy

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

density and pressure

Thermal conduction in solids mainly involves _______.

electron motion

When water boils, energy added to the water is counteracted by

energy carried away by steam.

Why is Millie's hand not burned when she holds it handspan above the escape valve of a pressure cooker?

expanding gas cools

Compared to a glass of ice water with ice, a glass of plain ice-cold water without ice on a warm day will warm up

faster

The process of convection occurs in

fluids

A poor conductor of heat is a

good insulator

Radiant energy from the Sun is composed of shorter wavelengths than radiation from the Earth because the Sun

has a higher temperature than the Earth.

The silver lining on the glass surfaces of a Thermos bottle reduces energy that is transferred by

radiation

What is sublimation?

change from solid to gas

Melting and freezing are

changes of phase. opposite processes

If the greenhouse effect on Earth were absent, Earth's average temperature would be about

-18 degrees c

Does a good insulator prevent heat from getting through it, or does it simply delay its passage?

A good insulator slows and delays the flow of heat from hot to cold.

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

All objects that emit radiation also absorb radiation.

Why does decreasing the temperature of a liquid make it freeze?

Decreasing temperature decreases the motion of the molecules, this allows forces to bind them together, vibrating about a position in a solid.

Distinguish between evaporation and boiling.

Evaporation happens at the surface, and it is a cooling process; boiling happens beneath the surface and is a cooling process.

What is evaporation and why is it a cooling process?

Evaporation is when a liquid turns into a gas; it is a cooling process because the fastest molecules evaporate most quickly, leaving behind the slower, cooler ones.

Why does increasing the temperature of a solid make it melt?

Increasing the temperature increases the vibration of the molecules, when enough energy goes into vibration, the attractive forces between molecules can no longer hold the molecules in place.

How does using a pressure cooker affect the amount of internal energy in the water inside the pressure cooker, and why?

It increases the amount of internal energy because it does not allow the heat to boil the water.

Which of the following would best describe the conductive properties of wood?

It is a good insulator.

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

It will continue to remain a good insulator.

What happens to water at room temperature if you decrease the atmospheric pressure around it?

It will first boil and then freeze.

Why is one able to walk on red-hot coals without getting one's feet burned?

The coals are not good conductors of heat.

How is the peak frequency of radiant energy related to the absolute temperature of the radiating source?

The peak frequency is proportional to the absolute temperature.

How does the pressure exerted by bubbles in the water compare with the atmospheric pressure when the temperature of water in an open pressure cooker is below 100∘ C and when it equals 100∘ C?

The pressure exerted by the bubbles is less than the atmospheric pressure below 100∘ C and equals the atmospheric pressure at 100∘ C.

Why does the pupil of the eye appear black?

The pupil allows light to enter the eye where it is absorbed and not reflected.

Water can be brought to a boil by

applying thermal energy and reducing air pressure on its surface

A soda can with a small amount of water is on a hot stove. Soon steam comes from its opening. When the can is quickly inverted into a pan of water, the can is crushed by

atmospheric pressure

Hot water will cool to room temperature faster in a

black pot

Conduction has most to do with electrons and atoms

bumping into one another

In a muggy region, the extra warmth you often feel is mainly due to

condensation

The dew that forms on a cold soda can when taken from a refrigerator is due to

condensation

If air were a better conductor than it is, nighttimes on Earth would be

considerbaly cooler

The process of boiling that occurs in water tends to _______.

cool the water

Pigs wallow in mud mainly to

cool themselves by evaporation

The process of boiling water tends to

cool water

Is the rate of cooling of a red-hot poker greater in a warm oven than in a cold room, or is the rate of cooling the same in both?

cooling is slower in the war oven

Newton's law of cooling applies to things that are

cooling, warming

If a volume of air is warmed, it expands. If a volume of air expands, it

cools

The temperature at which water freezes is the same as the temperature at which

ice melts

You can add heat without raising temperature to

ice. boiling water.

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

increase

Which moves faster in a gas at the same temperature?

light molecules

Glass in a florist's greenhouse blocks radiation of relatively

low frequencies

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

lower than its surroundings

When salt is introduced to water, the temperature at which freezing occurs is

lowered

Water can change phase to become ice by

lowering the surrounding air pressure .extraction of energy.

Do all the molecules in a liquid have about the same speed, or do they have a wide variety of speeds?

molecules have a wide range of speeds

Which of these are good conductors?

none of the above (feathers,snow,wood)

A good reflector of radiation is a

poor absorber of radiation

As water changes to ice, water molecules

release energy

When a gas changes phase to become a solid, energy is

released

Steam burns are much more damaging than boiling-water burns because steam

releases more thermal energy.

The wavelengths radiated by a high-temperature source are relatively _______.

short

The higher the temperature of an object, the

shorter the wavelengths it radiates.

In practice, a good insulator

slows heat flow

Peak frequency as noted on a radiation curve is directly proportional to the

temperature of the emitter.

Evaporation is a cooling process because

the more energetic molecules are able to escape the liquid

Waves emitted by the Sun and terrestrial wave emissions are

the same except for their frequencies and wavelengths.

If an object radiates more energy than it absorbs, its

thermal energy decreases. temperature decreases.

What do you use a pressure cooker for?

to prevent boiling and cooling

Convection currents in the air near a seashore are produced by

unequal heating of land and water.

How would you walk on red-hot coals without getting your feet burned?

walk fast