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