Chapter 8: Heat
if you triple the absolute temperature of an object, it will radiate energy
81 times faster
good absorbers of radiation
a good emitter of radiation
in the mountains. water boils at
a lower temperature than at sea level
if air were a better conductor that it is, at nighttime the earth would be
considerably colder
if your hands are being warmed by holding them above a flame, then the primary form of heat transfer is which process?
convection
Ice is put in a cooler in order to cool the contents. To speed up the cooling process, the ice can be
crushed
When a volume of air is compressed, its temperature
decreases
when water freezes, the entropy of the water
decreases
a good reflector of radiation is a
poor absorber of radiation
a good heat conductor is a
poor insulator
Increased air pressure on the surface of hot water tends to
prevent boiling
If holding hands to one side of a flame, the predominant form of heat transfer is what process?
radiation
if you hold your hands to one side of a flame, the predominant form of heat transfer that you will experience is
radiation
the planet earth loses heath mainly by
radiation
a refrigerator
removes thermal energy from inside the refrigerator
suppose you are served coffee at a restaurant before you are ready to drink it. In order for it to be the hottest when you are ready for it, you should add cream
right away
the primary reason why a sandy beach gets so hot on a sunny day is becuase
sand has a small specific heat
is it possible to transfer heat from a cold reservoir to a hot reservoir?
yes, but work will have to be done
Which would burn the most? A) 100g of water at 100 degrees C B) 100g of steam at 100 degrees C C) both would be equally damaging
(b) 100g of steam at 100c
Compared to a glass of ice water with ice in it, a glass of plain ice-cold water without ice on a warm day will warm up
FASTER
the kelvin temperature scale has the same size degree as the ___ scale and its zero is ___ lower
celsius / 273
hydrogen and oxygen molecules in a sample 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
evaporation is a cooling process because
more energetic molecules are able to escape the liquid
Food cooked in boiling water in the mountains cooks more slowly than cooked at sea level. If the temperature under the pot is increased, the food will cook
neither faster or slower
sea breezes on a beach are attributed to a difference between land and water with respect to what property?
specific heat
If molecules in a sample of gas moved so they completely missed each other, the gas's temperature would
stay the same
When heat is added to boiling water, its temperature
stays the same
at what temperature is water most dense ?
4 degrees Celsius
objects that radiate relatively well
absorb radiation relatively well
when a solid is changes to a liquid phase, the solid
absorbs energy
saturation occurs in air when the
air contains as many water molecules as it can contain at a given temperature
if you were caught in freezing weather with only a candle for heat, you would be warmer in
an igloo
heat engines, such as an automoblie engine, are more efficient when run
at high temperatures
as entropy of a system increases, energy in the system
becomes more diluted
Cold water will warm to room temperature faster in a
black pot verses a silver pot
hot water will cool to room temperature faster in a
black pot verses a silver pot
If you want to cook eggs by boiling them while in the mountains, then compared to sea level cooking, you should
boil the eggs for a longer time
a heat pump
can acts as heater, an air-conditioner, though only works wells in moderate climates, but can also by a reversible heat engine
An object will normally be a net radiator of energy when its thermal energy is...
can't answer, because thermal energy is not temperature
Consider a steaming aluminum soda-pop can that contains a small amount of boiling water. When it is quickly inverted into a bath of cooler water the can is dramatically crushed by atmospheric pressure. This occurs because the pressure inside the can is rapidly reduced by
condensation of steam inside
by what primary heat transfer mechanism does one end of a metal spoon become hot when the other end is place in boiling water
conduction
the space between the inner walls of a thermos bottle is evacuated to minimize heat transfer by
conduction and convection
a substance can absorb heat energy by the process of
convection
warm air raises because faster moving molecules tend to move to regions of less
density and pressure
the second law of thermodynamics leads us to conclude that
disorder in the universe is increasing with the passage of time
The work output of a perfectly constructed heat engine
equals the difference between its heat intake and heat exhaust
if a volume of air is warmed, it
expands
energy transfer by convection is primarily restricted to
fluids
steam burns are more damaging than burns caused by boiling water because steam
gives up additional energy when it condenses, and has more energy per kilogram than boiling water
when a vapor condenses
heat energy leaves the substance
when a vapor ondenses
heat energy leaves the substance
Food in a pressure cooker is cooked faster because of the
higher temperature
an adiabatic process
involves no net heat entering or leaving a system
your feet feel warmer on a rug than on a tile floor because the rug
is a better insulator than tile
when bringing water to a boil in the mountains, the time needed to reach the boiling point is
less than at sea level
double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by
less than twice
convection can occur
only in liquids and gases
The silver coating on the glass surfaces of a Thermos bottle reduces energy that is transferred by
radiation
by what primary heat transfer mechanism does the sun warm the earth
radiation
An inventor discovers a harmless and tasteless salt, which, when added to water changes its boiling point. The market value for this salt will be best if the salt
raises the boiling point of water
when liquids change to a solid phase, they
release energy
when a gas is changed to a liquid phase, the gas
releases energy
metals are both good heat conductors and also god electrical conductors because of the
similarity between thermal and electrical conductive properties
A chunk of ice (T = -20°C) is added to a thermally insulated container of cold water (T = 0°C). What happens in the container?
some of the water freezes and the chunk of ice gets larger
what happens to water when heated from 0c degrees to 4c
the density increases is the water
a water-filled paper cup held in a flame will not catch fire. this is becuase
the paper cup cannot become appreciably hotter than the water it contains
what happens to a given mass of water when cooled between 4 and 0c
the water expands
We are warmed by condensation because water molecules in the air that strike our bodies
transfer some of their kinetic energy to us
geothermal heating or cooling
uses the ground as a heath source of heat sink
The cooling effect inside a refrigerator is produced by
vaporizing the refrigeration gas into a liquid
by blowing on a cup of hot coffee
we remove water vapor above the coffee so that further evaporation is enhanced
suppose you walk on red hot coals with bare feet. Providing bits of coal do not stick to your feet, it would be best if your feet are
wet