Test 4 Review B
Water will evaporate quicker if it
C) is spread out in a thin sheet. D) is surrounded by dry air. E) is preheated to 100 degrees C.
Compared to a giant iceberg, a hot cup of coffee has
higher temperature, but less internal energy.
When snow forms in clouds, the surrounding air
warms
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.
Metals are both good heat conductors and good electrical conductors because of the
looseness of outer electrons in metal atoms.
A substance that heats up relatively quickly has a
low specific heat.
One of the main reasons one can walk barefoot on red-hot coals of wood without burning the feet has to do with
low thermal conductivity of the coals.
To say that evaporation is a cooling process is to say that the
more energetic particles escape.
Systems that are left alone, tend to move toward a state of
more entropy
Consider a closed, sealed can of air placed on a hot stove. The contained air undergoes an increase in
two of these.
The white-hot sparks that strike your skin from a 4th-of-July-type sparkler do not harm you because
the energy per molecule is high, but little energy is transferred because of the few molecules in the spark.
On a humid day, water condenses on the outside of a glass of ice water. This phenomenon occurs mainly because of
the saturation of cooled air.
A temperature inversion occurs when the upper layers of air are
warmer than the lower regions of air.
The ideal efficiency for a heat engine operating between temperatures of 2700 C and 300 C is
# T_H = 2700C +273 = 2973 K # T_C = 300C + 273 = 573 K # e = (T_H-T_C)/T_H = (2973-573)/2973 = 2400/2973 = 0.807*100% = 81%
The lowest temperature possible in nature is
-273 degrees C
Before ice can form on a lake, all the water in the lake must be cooled to
4 degrees C.
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 ideal efficiency for a heat engine operating between temperatures of 2700 K and 300 K is
89%.
A temperature difference of 10 degrees Celsius is also equal to a temperature difference of 10 on the
Kelvin scale.
A good absorber of radiation is a
good emitter of radiation
The reason the sun's radiant energy is of shorter wavelengths than the Earth's is because the sun
has a higher temperature than the Earth.
An adiabatic process is characterized by the absence of
heat exchange
An object will normally be a net radiator of energy when its temperature is
higher than its surroundings.
To wholly convert a given amount of heat energy into mechanical energy is
impossible regardless of the technique used.
The molecules in a room-temperature glass of water jostle around at
a great variety of speeds.
The fact that desert sand is very hot in the day and very cold at night is evidence that sand has
a low specific heat.
Objects that radiate relatively well,
absorb radiation relatively well.
When a solid is changed to a liquid state, the solid
absorbs energy.
If you were caught in freezing weather with only a candle for heat, you would be warmer in
an igloo.
A heat engine would have 100 percent efficiency if its input reservoir were
any finite temperature if the exhaust sink were at absolute zero.
Pour a liter of water at 40 degrees C into a liter of water at 20 degrees C and the final temperature of the two becomes
at or about 30 degrees C.
Cold water will warm to room temperature faster in a
black pot.
A quantity of water has more entropy when it is
boiling
Substances absorb heat energy by the process of
convection, conduction, radiation
Blow on your hand with your open mouth and you feel the warmth of your breath. Pucker your lips so your breath expands as you blow, and your breath is
cooler
If a volume of air is warmed, it expands. If a volume of air expands, it
cools
Ice is put in a cooler to cool the contents. To speed up the cooling process, the ice can be
covered with salt.
Entropy can be
created but not destroyed
When you touch a cold piece of ice with your finger, energy flows
from your finger to the ice.
As a piece of metal with a hole in it cools, the diameter of the hole
decreases
If a blob of air is swept upward, with no heat input or output, its temperature
decreases
If glass expanded more than mercury, then the column of mercury in a mercury thermometer would rise when the temperature
decreases
When a system does work and no heat is added to the system, its temperature
decreases
When heat is added to boiling water, its temperature
does not change.
Hot water has a relatively high rate of
evaporation
When water at 4 degrees C is heated it expands. When water at 4 degrees C is cooled, it
expands
Food cooked in boiling water at a mountain top cooks slower than when cooked at sea level. If the temperature under the pot of boiling water is increased, the food will cook
no differently than it did before the increase.
Increased air pressure on the surface of hot water tends to
prevent boiling.
The planet Earth loses heat mainly by
radiation.
A refrigerator
removes internal energy from inside the refrigerator.
