physics study guide
2nd law of thermodynamics
heat goes high to low
Some molecules are able to absorb large amounts of energy in the form of internal vibrations and rotations. Materials composed of such molecules would have ______.
high specific heat capacities
It is possible to wholly convert a given amount of heat energy into mechanical energy.
false
Entropy measures ______.
messiness
Ceramic automobile engines that can operate at higher temperatures will be ______.
more efficient
Systems that are left alone tend to move toward a state of _____.
more entropy
Which has the higher specific heat capacity, water or sand?
Water
how many Joules of heat are needed to raise the temperature equation
(delta)Q=mc(delta)T
Q = m c (Tf - Ti)
..
mass of spinning bag
FG = M G fg= mv^2/r v=
efficiency of engines equation
Thot - Tcold / Thot
Measurements inside a sealed container show that the pressure exerted by a gas increases as the thermal energy of the gas increases. Which of the following best explains this pressure increase?
The gas molecules move faster and strike the container walls more frequently.
When work is done by a system on something else, the temperature of the system decreases.
True, since the work-energy is leaving the system, the energy of the system decreases and therefore the temperature as well.
work capabilities of heat engine equation
W = Qh - Ql
If a bicycle pump had no friction, would it get hot pumping air?
Yes, U=Q+W, the work increases the molecular energy
temperature is related mostly to the
average molecular kinetic energy in a substance
the energy content in a food is usually determined by
burning the food
1st law of thermodynamics
conservation of energy (heat)
The first law of thermodynamics is a restatement of the _____.
conservation of energy Correct
When work is done by a system and no heat is added to it, the temperature of the system ______.
decreases
putting work on something _________ entropy
decreases
heat is the
energy transferred between objects because of a temperature difference
If all the friction could be eliminated in a heat engine, its efficiency would be 100%.
false
The greater the difference in temperature between the input reservoir for a heat engine, the ______.
greater the efficiency
The largest extremes in temperature are usually experienced _____.
in the middle of a continent
When a volume of air is compressed and no heat enters or leaves, the air temperature will _____.
increase
As a system becomes more disordered, entropy ______.
increases
When mechanical WORK is done on a system, there can be an increase in its _____.
internal energy and temperature
heat is measured in
kilocalories, calories, and joules
If the specifc heat capacity of water were higher than it is, lakes would be ______.
less likely to freeze
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 capacity
Specific heat capacity is related to the amount of internal energy ______.
needed to change the temperature of one kilogram of a substance one degree
Entropy is closely related to the _____.
second law of thermodynamics
Two identical blocks of iron, one at 10 degrees C and the other at 20 degrees C, are put in contact. Suppose the cooler block cools to 5 degrees C and the warm block warms to 25 degrees C. This would violate the ______.
second law of thermodynamics
internal energy is the
total amount of energy contained in an object. "U"
Efficiency in a heat engine is increased when there is a greater difference in input and output temperatures.
true
It is possible to totally convert a given amount of mechanical energy into heat.
true
Systems left alone tend to move to a state of greater entropy
true
Cool a sample of air from zero on the Celsius scale to near zero on the absolute scale and the air loses ______.
volume and pressure
The reason an ocean's temperature doesnt vary much from one season to the next is that _____.
water has a high specific heat capacity