PHYS 101 Unit 4

The earth's atmosphere gets most of its heat

near the surface of the earth

Increased air pressure on the surface of hot water tends to

prevent boiling

The lowest temperature possible in nature is

-273 degrees C

A volume of air has a temperature of 0 degrees Celsius. An equal volume of air that is twice as hot has a temperature of

273 degrees C

Stored potatoes, beets, and rutabagas freeze at temperatures below zero degrees Celsius (rather than at exactly zero) because

The water in them contains dissolved sugars and salts.

The fact that a thermometer "takes its own temperature" illustrates

Thermal Equilibrium

The molecules in a room-temperature glass of water jostle around at

a great variety of speeds.

A good reflector of radiation is

a poor absorber of radiation

Suppose you want to save energy and you're going to leave your warm house for a half hour on a cold day. You should turn the thermostat

down

Between 0 degrees Celsius and 8 degrees Celsius a red-dyed-water-in-glass thermometer would

give ambiguous readings.

For increased atmospheric pressure, the boiling temperature of a liquid

goes up

A good absorber of radiation is a

good emitter of radiation

Which of the following expands most when the temperature is increased? Equal volumes of

helium.

Ice tends to form first at the

surface of bodies of water

Both black and white road surfaces absorb sunlight. At the end of a sunny day the warmer road surface will be

the black surface

Boiling water does not increase in temperature when additional heat is applied because

the increased heating produces increased boiling, and therefore increased cooling.

Evaporation is a cooling process because

the more energetic molecules are able to escape the liquid

We are warmed by condensation because water molecules in the air that strike our bodies

transfer some of their kinetic energies to us.

Room temperature on the Kelvin scale is about

300 K

One hundred joules of heat is added to a system that performs 60 joules of work. The internal energy change of the system is

40 J

The calories needed to change 10 grams of ice at zero degrees C to steam at 100 degrees C is

7200

The technology for orbiting solar power plants

already exists

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.

Ice is put in a cooler to cool the contents. To speed up the cooling process, the ice can be

covered with salt

Sue's refrigerator is built into the wall of her kitchen, so that it exhausts heat to the outdoors rather than into the room. If Sue tries to cool her kitchen by leaving the refrigerator door open, the room temperature will

decrease at least slightly.

As a piece of metal with a hole in it cools, the diameter of the hole

decreases

We feel uncomfortably warm on a muggy day because water molecules are

evaporating and condensing on our bodies at the same rate.

Wrapping a hot potato in aluminum foil significantly reduces the rate at which it cools by

evaporation.

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.

Which of the following contracts most when the temperature is increased? Equal volumes of

ice water.

To wholly convert a given amount of heat energy into mechanical energy is

impossible regardless of technique used.

As a system becomes more disordered, entropy

increases

Your feet feel warmer on a rug than on your tile floor because your rug

is a better insulator than your tile.

Ice has a lower density than water because ice

is made of open-structured, hexagonal crystals.

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 average speed of its molecules

less than doubles

Metals are both good heat conductors and good electrical conductors because of the

looseness of outer electrons in metal atoms

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 state, they

release energy

If you double the pressure of an ideal gas while keeping the temperature constant, the average kinetic energy of the molecules

remains unchanged

A water-filled paper cup held in a flame will not catch fire. This is because

the paper cup cannot become appreciably hotter than the water it contains.

Waves emitted by the sun and terrestrial wave emissions are

the same except for frequencies and wavelengths

If a solid object radiates more energy than it absorbs, its

thermal energy and temperature decreases

Which of the following expands most when the temperature is lowered? Equal volumes of

water at 4 degrees C.

During a very cold winter, water pipes sometimes burst. The reason for this is

water expands when freezing.