Physics Chapter 7
if you triple the absolute temperature of an object, it will radiate energy
81 times faster
in the mountains, water boils at
a lower temperature than at seal level
what primary heat transfer mechanism does on end of a metal spoon becomes hot when the other end is placed 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
conduction convection and radiation
if air were a better conductor than 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
when a volume of air is compressed, its temperature
decreases
when water freezes, the entropy of the water
decreases
warm air rises because faster moving molecules tend to move to regions of less
density and pressure
what happenes to water when its temp is reduce from 12 to 4 celsius
density increases
what happens to water when heated from 0 degrees to 4 celsius
density increases
the second law of thermodynamics leads us to conclude that
disorder in the universe is increasing with the passage of time
if a volume of air is warmed, it
expands
what happens to a given mass of water when cooled between 4 and 0 celsius
expands
a good reflector of radiation is a
poor absorber of radiation
increased air pressure on the surface of hot water tends to
prevent boiling
by what primary heat transfer mechanism does the sun warm the earth
radiation
if holding hands to one side of a flame,the predominant form of heat transfer is what process?
radiation
the planet earth loses heat mainly by
radiation
the silver coating on the glass surfaces of a thermos bottle reduces energy that is transferred
radiation
the primary reason why a sandy beach gets so hot on a sunny day is because
sand has a small specific heat
evaporation is a cooling process because
the more energetic molecules are able to escape the liquid
is it possible to transfer heat from a cold reservoir to a hot reservoir
yes but work will have to be done
the cooling effect inside a refrigerator is produced by
vaporizing the refrigeration liquid
objects that radiate relatively well
absorb radiation relatively well
saturation occurs in air when the
air contains as many water molecules as it can contain in a given temperature
if you were caught in freezing weather with only a candle for heat, you would be warmer in
an igloo
cold water will warm to room temperature faster in a
black pot
hot water will cool to room temperature faster in a
black pot
an object will normally be a net radiator of energy when its thermal energy is
can't say
which material is a good thermal insulator
concrete
consider a steaming aluminum soda pop can that contains a small amount of boiling water. when it is quickly invented 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
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
energy transfer by convection is primarily restricted to
fluids
steam burns re more damaging than burns caused by boiling water because steam
gives up additional energy when it condenses and has more energy per kg than boiling water
a good absorber of radiation is a
good emitter of radiation
a good heat conductor is a
good insulator
when a vapor condenses
heat energy leaves the substance
which heat is the greatest
heat necessary to vaporize 1kg of boiling water
food in a pressure cooker is cooked faster because of the
higher temperature
your feet feel warmer on a rug than on a tile floor because the rug
is a better insulator than tile
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
when bringing water to a boil in the mountains, the time needed to reach boiling point is
less than at sea level
if a poor absorber of radiation were a good emitter, its temperature would be
less than its surroundings
double the absolute temperature of helium gas, the molecules of helium speed up by
less than twice
metals are both good heat conductors and also good electrical conductors bc of the
looseness of outer electrons in metal atoms
convection can occur
only in liquids and gases
a chunk of ice is added to a thermally insulated container of cold water. what happens in the container
some of the water freezes and the chunk of ice gets larger
if molecules in a sample gas moved so they completely missed each other, the gas's temperature would
stay the same
when heat is added to boiling water, the water temperature
stays the same
which involved the larger number of calories
the condensation of 1g of steam at 100 celsius to 100 celsius water
a water-filled paper cup held in a flame will not catch fire. this is because
the paper cup cannot become appreciately hotter than the water it contains
we are warmed by condensation because water molecules in the air that strike our bodies
transfer some of their kinetic energies to us