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.