Physics Test 3
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When you touch a cold piece of ice w your finger, energy flows...
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from your finger to the ice
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the fact that a thermometer takes its own temperature illustrates...
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thermal equilibrium
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the lowest possible temperature in nature
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-273 degrees C
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heat energy is measured in units of...
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calories and joules
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double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by...
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less than twice
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compared to a giant iceberg, a hot cup of coffee has
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higher temperature but less thermal energy
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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...
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at or about 30 C
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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...
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the iron will have the higher temp
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T or F: it is possible to wholly convert a given amount of heat energy into mechanical energy
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False
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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...
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cooler
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when 100 J of heat is added to a system that performs 60 J of work, the thermal energy change of the system is...
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40 J
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when mechanical work is done on a system, there can be an increase in its...
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thermal energy and temperature
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when a volume of air is compressed and no heat enters or leaves, the air temp will...
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increase
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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...
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second law of thermodynamics
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if you run a refrigerator in a closed room w the refrigerator door open, the room temp will...
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increase
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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...
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5 C + 273 = 278 K x 2 = 556 K - 273 = 283 C
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A container of air is at atmospheric pressure and 27 C. To double the pressure in the container, it should be heated to...
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27 C + 273 = 300 K x 2 = 600 K - 273 = 327 C
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entropy is closely related to the...
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second law of thermodynamics
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which warms up the fastest when heat is applied: water, glass, iron, or wood?
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iron
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The moderate temps of islands throughout the world has much to do with water's...
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high specific heat capacity
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The fact that desert sand is very hot in day and very cold at night is evidence that sand has a...
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low specific heat capacity
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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...
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copper
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when an iron ring is heated, the hole becomes...
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larger
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when a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. the reason for this is...
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copper expands more than iron
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Which of the following expands most when the temp is increased? wood, helium, iron, or ice water?
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helium
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which of the following contracts most when the temp is decreased? iron, wood, helium, or water?
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helium
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Consider a sample of water at 0 C. If the temp is slightly increased, the volume of water...
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contracts
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During a very cold winter, water pipes sometimes burst. The reason for this is...
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water expands when freezing
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Ice has a lower density than water because ice...
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is made of open-structured hexagonal crystals
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before ice can form on a lake, all the water in the lake must be cooled to...
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4 C
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the temp at the bottom of lake tahoe at this moment is...
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exactly 4 C
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a substance can absorb heat energy by the process of...
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radiation, conduction, and convection
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a good heat conductor is a...
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poor insulator
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a water filled paper cup held in a flame will not catch fire. this is because...
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the paper cup cannot become hotter than the water it contains
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energy transfer by convection is primarily restricted to...
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fluids
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at the same temp, which move w greater speed in the air: very light or heavier molecules?
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very light molecules
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when a volume of air is compressed, its temp...
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increases
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in a mixture of hydrogen, oxygen, and nitrogen gas, the molecules w the greatest avg speed are those of...
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hydrogen
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the higher the temp of an object, the...
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shorter the wavelengths it radiates
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if an object radiates more energy than it absorbs, its...
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thermal energy and temp decreases
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hot water will cool to room temp faster in a...
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black pot
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an object will normally be a net radiator of energy when its temp is...
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higher than its surroundings
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if air were a better conductor than it is, at nighttime the earth would be...
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considerably colder
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if a poor absorber of radiation were a good emitter, its temp would be...
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less than its surroundings
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a good reflector of radiation is a...
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poor absorber of radiation
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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...
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right away
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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...
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off altogether
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Newton's law of cooling applies to objects that are...
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both heating and cooling
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the silver coating on the glass surfaces of a thermos bottle reduces energy that is transferred by...
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radiation
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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...
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wet
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to melt 50 g of 0 C ice requires: 25, 50, or 80 calories?
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none of these
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a refrigerator...
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removes thermal energy from inside the refrigerator
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ice is put in a cooler in order to cool the contents. to speed up the cooling process, the ice can be...
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crushed
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the # of grams of ice that can be melted by 1 g of 100 C steam is...
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8 g
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the molecules in a room temp glass of water jostle around at...
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a great variety of speeds
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evaporation is a cooling process bc...
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the more energetic molecules are able to escape the liquid
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a hot dog pants to...
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help evaporation occur in its mouth and bronchial tract
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steam burns are more damaging than burns caused by boiling water bc steam...
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give up additional energy when it condenses and has more energy per kg than boiling water
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we are warmed by condensation bc water molecules in the air that strike our bodies...
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transfer some of their kinetic energy to us
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increased air pressure on the surface of hot water tends to...
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promote boiling
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when heat is added to boiling water, water temp...
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stays the same
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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...
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faster
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food in a pressure cooker is cooked faster bc of the...
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higher temp
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if you want to cook eggs by boiling them while in the mountains, then compared to sea level cooking, you should...
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boil eggs for a longer time
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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...
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raises the boiling point of water
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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...
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condensation of steam inside
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when a solid is changed to a liquid phase, the solid...
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absorbs energy
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which would burn the most: 100 g of water at 100 C or 100 g of steam at 100 C?
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100 g of steam at 100 C
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total energy of submicroscopic particles that make up a substance
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thermal energy
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measure of hotness or coldness of substances, related to avg kinetic energy per molecule in a substance
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temperature
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equation for finding F when you know C
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F = 1.8 (C) + 32
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equation for finding C when you know F
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C = 1/1.8 (F - 32)
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theoretical temperature at which a substance possesses no kinetic energy
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absolute zero
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how far apart are Celcius and Kelvin scales? (equation)
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273 degrees, K = C + 273
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thermal energy that flows from a substance of higher temp to a substance of lower temp
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heat
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equation for heat
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Q (heat) = mc triangle T (change in temp)
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when is water at its heaviest?
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4 C
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first law of thermodynamics
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conservation of energy
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second law of thermodynamics
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quality of energy
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third law of thermodynamics
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can't have temp below absolute zero
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by physical contact; high conductors (metals) and low insulators (wood, styrofoam)
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conduction
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by fluid motion; natural and forced
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convection
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by electromagnetic waves; requires direct view; does not need a medium
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radiation
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glass is transparent to visible waves, but opaque to infrared waves
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greenhouse effect
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different phases of radiation
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absorption, emission, reflection, transmission
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Newton's Law of Cooling
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rate (of heating or cooling) ~ triangle T
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what happens to the temp of a gas when it compresses?
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becomes hot
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what happens to the temp of a gas when it expands?
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becomes cool
