Physics Chapter 12 Conceptual
if you triple absolute temperature of an object, it will radiate energy
81 times faster
conduction
Conduction transfers heat via direct molecular collision. An area of greater kinetic energy will transfer thermal energy to an area with lower kinetic energy. Higher-speed particles will collide with slower speed particles. The slower-speed particles will increase in kinetic energy as a result
H and O molecules in a sample gas have the same temperature, this means, on avg, the H molecules have the same
KE, but more speed
radiation
Thermal radiation generates from the emission of electromagnetic waves. These waves carry the energy away from the emitting object. Radiation occurs through a vacuum or any transparent medium (either solid or fluid). Thermal radiation is the direct result of random movements of atoms and molecules in matter
in the mountains, water boils at
a lower temperature than at sea level
by what primary heat transfer does one end of a metal spoon become 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, radiation, and evaporation
ice is put into a cooler in order to cool the contents. To speed up the cooling process, the ice can be
crushed
when water freezes, the entropy of the water
decreases
what happens to a given mass of water when cooled between 4 and 0 C
expands
a good reflector of radiation is a
poor absorber of radiation
a good head conductor is a
poor insulator
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
if you hold your hands to one side of the flame, the predominant form of heat transfer that you will experience is
radiation
the planet earth loses heat mainly by
radiation
the silver coating on the glass surface of a Thermos bottle reduces energy that is transferred by
radiation
an inventor discovers a harmless and tasteless salt, which, when added to water changes to 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
a refrigerator
removes thermal energy from inside the fridge
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 to hot on a sunny day is
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 the refrigerator is produced by
vaporizing the refrigeration liquid
which one of the following statements best explains why metal pipes cary water often burst during the cold winter months
water expands upon freezing while the metal contracts a lower temperatures
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 read hot coals with bare feet. Providing bits of coal do not stick to your feet, it would be best if you feet are
wet
which would burn the most
100 g of steam at 100 C
what is the theoretical efficiency of a Carnot engine that operates between 600 K and 300 K
50%
objects that radiate well
absorb radiation well
when a solid is changed to a liquid, the solid
absorbs energy
saturation occurs in air when the
air contains as many water molecules as it can contain at a given temperature
cold water will warm to room temperature faster in a
black pot
hot water will cool to room temperature faster in a
black pot
if you want to cook eggs by boiling them while in the mountains, then compared to sea level, you should
boil the eggs for a longer time
an object will normally be a net radiator of energy when its thermal energy is
cant say, thermal energy is not temperature
Which material is a good thermal insulator
concrete
consider steaming aluminum 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 the atm pressure. The 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 water without ice on a warm day will warm up
faster
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 square kilogram than boiling water
a good absorber of radiation is a
good emitter of radiation
when a vapor condenses
heat energy leaves the substance
which heat is the greatest
heat necessary to vaporize 1 kg of boiling water
if a poor absorber of radiation were a good emitter, its temperature would be
less than its surroundings
food in a pressure cooler is cooked faster because of the
higher temperature
your feet fell warmer on a rug than on a tile floor because a rug
is a better insulator than tile
when bringing water to a boil in the mountains, the time needed to reach boiling point is
less than at sea level
double up the absolute temperature of He gas, and the molecules of He speed up by
less than twice
metals are both good heat conductors and also good electrical conductors because
looseness of outer electrons in metal atoms
food cooked in boiling water in the mountains cooks slower than when cooked at sea level. If the temperature under the pot in increased, the food will cook
neither slower or faster
convection can occur
only in liquids and gases
a chunk of ice (20 C) is added to a thermally insulated container of cold water (O C). What happens in the container
some of the water freezes and the chunk of ice gets larger
sea breezes on a beach area attributed to a difference between land and water with respect to what property
specific heat
if a molecule 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 involves the larger number of calories
the condensation of 1 g of steam at 100 C to 100 C of water
a water filled paper cup held in a flame will not catch fire because
the paper cup cannot become appreciably hotter than the water it contains
we are warmed by condensation because water molecules in the air strike our bodies
transfer some of the KE to us
convection
When a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along. This type of heat transfer is called convection
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
convection
warm air rises because faster moving molecules tend to move to regions of less
density and pressure
what happens to water when heated from 0 degrees C to 4 C
density increases
what happens to water when its temperature is reduced from 12 degree to 4
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