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88 terms

Physics Test 3

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When you touch a cold piece of ice w your finger, energy flows...
from your finger to the ice
the fact that a thermometer takes its own temperature illustrates...
thermal equilibrium
the lowest possible temperature in nature
-273 degrees C
heat energy is measured in units of...
calories and joules
double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by...
less than twice
compared to a giant iceberg, a hot cup of coffee has
higher temperature but less thermal energy
pour a liter of water at 40 degrees C into a liter of water at 20 degrees C and the final temp of the two becomes...
at or about 30 C
a piece of iron and a cup of water both have the same temperature. if they are heated so the thermal energy of each doubles...
the iron will have the higher temp
T or F: it is possible to wholly convert a given amount of heat energy into mechanical energy
False
blow on your hand w your open mouth and you feel warmth of your breath. pucker your lips so your breath expands as you blow and your breath is...
cooler
when 100 J of heat is added to a system that performs 60 J of work, the thermal energy change of the system is...
40 J
when mechanical work is done on a system, there can be an increase in its...
thermal energy and temperature
when a volume of air is compressed and no heat enters or leaves, the air temp will...
increase
two identical blocks of iron, one at 10 C and the other at 20 C, are put in contact. suppose the cooler block cools to 5 C and the warmer block warms to 25 C. This would violate the...
second law of thermodynamics
if you run a refrigerator in a closed room w the refrigerator door open, the room temp will...
increase
Consider a piece of metal that is at 5 C. If it is heated until it has twice the thermal energy, its temp will be...
5 C + 273 = 278 K x 2 = 556 K - 273 = 283 C
A container of air is at atmospheric pressure and 27 C. To double the pressure in the container, it should be heated to...
27 C + 273 = 300 K x 2 = 600 K - 273 = 327 C
entropy is closely related to the...
second law of thermodynamics
which warms up the fastest when heat is applied: water, glass, iron, or wood?
iron
The moderate temps of islands throughout the world has much to do with water's...
high specific heat capacity
The fact that desert sand is very hot in day and very cold at night is evidence that sand has a...
low specific heat capacity
aluminum has a specific heat capacity more than twice that of copper. place equal masses of aluminum and copper wire in a flame and the one to undergo the fastest increase in temp will be...
copper
when an iron ring is heated, the hole becomes...
larger
when a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. the reason for this is...
copper expands more than iron
Which of the following expands most when the temp is increased? wood, helium, iron, or ice water?
helium
which of the following contracts most when the temp is decreased? iron, wood, helium, or water?
helium
Consider a sample of water at 0 C. If the temp is slightly increased, the volume of water...
contracts
During a very cold winter, water pipes sometimes burst. The reason for this is...
water expands when freezing
Ice has a lower density than water because ice...
is made of open-structured hexagonal crystals
before ice can form on a lake, all the water in the lake must be cooled to...
4 C
the temp at the bottom of lake tahoe at this moment is...
exactly 4 C
a substance can absorb heat energy by the process of...
radiation, conduction, and convection
a good heat conductor is a...
poor insulator
a water filled paper cup held in a flame will not catch fire. this is because...
the paper cup cannot become hotter than the water it contains
energy transfer by convection is primarily restricted to...
fluids
at the same temp, which move w greater speed in the air: very light or heavier molecules?
very light molecules
when a volume of air is compressed, its temp...
increases
in a mixture of hydrogen, oxygen, and nitrogen gas, the molecules w the greatest avg speed are those of...
hydrogen
the higher the temp of an object, the...
shorter the wavelengths it radiates
if an object radiates more energy than it absorbs, its...
thermal energy and temp decreases
hot water will cool to room temp faster in a...
black pot
an object will normally be a net radiator of energy when its temp is...
higher than its surroundings
if air were a better conductor than it is, at nighttime the earth would be...
considerably colder
if a poor absorber of radiation were a good emitter, its temp would be...
less than its surroundings
a good reflector of radiation is a...
poor absorber of radiation
Suppose you are served coffee at a restaurant before you are ready to drink it. in order for it to be hottest when you are ready for it, you should add cream...
right away
suppose you want to save energy and you're going to leave your cool house for a half hr on a hot day. you should turn the temp setting on the AC...
off altogether
Newton's law of cooling applies to objects that are...
both heating and cooling
the silver coating on the glass surfaces of a thermos bottle reduces energy that is transferred by...
radiation
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
to melt 50 g of 0 C ice requires: 25, 50, or 80 calories?
none of these
a refrigerator...
removes thermal energy from inside the refrigerator
ice is put in a cooler in order to cool the contents. to speed up the cooling process, the ice can be...
crushed
the # of grams of ice that can be melted by 1 g of 100 C steam is...
8 g
the molecules in a room temp glass of water jostle around at...
a great variety of speeds
evaporation is a cooling process bc...
the more energetic molecules are able to escape the liquid
a hot dog pants to...
help evaporation occur in its mouth and bronchial tract
steam burns are more damaging than burns caused by boiling water bc steam...
give up additional energy when it condenses and has more energy per kg than boiling water
we are warmed by condensation bc water molecules in the air that strike our bodies...
transfer some of their kinetic energy to us
increased air pressure on the surface of hot water tends to...
promote boiling
when heat is added to boiling water, water temp...
stays the same
compared to a glass of ice water w ice in it, a glass of plain ice cold water w/o ice on a warm day will warm up...
faster
food in a pressure cooker is cooked faster bc of the...
higher temp
if you want to cook eggs by boiling them while in the mountains, then compared to sea level cooking, you should...
boil eggs for a longer time
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
consider a steaming aluminum soda pop can that contains a small amt of boiling water. when its quickly inverted into a bath of cooler water, the can is dramatically crushed by atmospheric pressure. this occurs bc the pressure inside the can is rapidly reduced by...
condensation of steam inside
when a solid is changed to a liquid phase, the solid...
absorbs energy
which would burn the most: 100 g of water at 100 C or 100 g of steam at 100 C?
100 g of steam at 100 C
total energy of submicroscopic particles that make up a substance
thermal energy
measure of hotness or coldness of substances, related to avg kinetic energy per molecule in a substance
temperature
equation for finding F when you know C
F = 1.8 (C) + 32
equation for finding C when you know F
C = 1/1.8 (F - 32)
theoretical temperature at which a substance possesses no kinetic energy
absolute zero
how far apart are Celcius and Kelvin scales? (equation)
273 degrees, K = C + 273
thermal energy that flows from a substance of higher temp to a substance of lower temp
heat
equation for heat
Q (heat) = mc triangle T (change in temp)
when is water at its heaviest?
4 C
first law of thermodynamics
conservation of energy
second law of thermodynamics
quality of energy
third law of thermodynamics
can't have temp below absolute zero
by physical contact; high conductors (metals) and low insulators (wood, styrofoam)
conduction
by fluid motion; natural and forced
convection
by electromagnetic waves; requires direct view; does not need a medium
radiation
glass is transparent to visible waves, but opaque to infrared waves
greenhouse effect
different phases of radiation
absorption, emission, reflection, transmission
Newton's Law of Cooling
rate (of heating or cooling) ~ triangle T
what happens to the temp of a gas when it compresses?
becomes hot
what happens to the temp of a gas when it expands?
becomes cool