Chapter 24 Review
distinguish between the first and second laws of thermodynamics in terms of whether or not exceptions occur
1st-no exceptions 2nd-exceptions
in buildings that are electrically heated, turning the lights on
doesn't waste energy
if all the friction could be eliminated in a heat engine its efficiency would be 100%
false
When a volume of air is compressed and no heat enters or leaves, the air temperature will
increase
entropy measures
messiness
The ideal efficiency for a heat engine operating between temperatures of 2050K and 310K is
85%
adiabatic processes occur in
all of the above
It is possible to wholly convert a given amount of heat energy into mechanical energy
false
if the internal energy of a volume of air at 10C doubled its temperature would then be 20C
false
ceramic automobile engines that operate at higher temperature will be
more efficient
Systems that are left alone, tend to move toward a state of
more entropy
an absolute temperature of 110 K is the same as what C
-163 C
The lowest possible temperature in nature is
-273 degrees C
calculate the ideal efficiency of a power plant that runs between temperatures 400K and 150K
62.5%
the temperature of an object is raised by 70C. this is equivalent to what increase in its absolute temperature
70 C
an absolute temperature of 473 K is the same as what C
200 C
80 joules of heat is added to a system that performs 55 Joules of work. The internal energy change of the system is
25J
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
at what temperature would the molecules of a gas have twice the average kinetic energy they have at 26C room temperature
325
there is a type of power plant known at OTEC that operates on the temperature difference between warm surface water and cool deep waters. What is the Carnot efficiency of such a plant if the surface water is 25C and the deep water is 4C
84%
cool a sample of air from zero on the Celsius scale to near zero on the absolute scale and the air loses
both A & B
when mechanical work is done on a system there can be an increase in its
both of the above
The first law of thermodynamics is a restatement of the
conservation of energy
if a volume of air is swept upward with no heat input or output its temperature
decreases
when work is done by a system and no heat is added to it the temperature of the system
decreases
air high in the atmosphere that plunges downward tends to cool
false
the greater the difference in temperature between the input reservoir and output reservoir for a heat engine, the
greater the efficiency
how does the second law of thermodynamics relate to the direction of heat flow
heat flows from hot to cold
pull a closed plastic bag of dry air quickly down from a high elevation and the bag of air will become
hotter
give two reasons why a tire pump becomes hotter when used to pump a tire
increase in internal energy/pressure and increase in external work
Suppose the temperature of the input reservoir in a heat engine doesn't change. As the sink temperature is lowered, the efficiency of the engine
increases
as a system becomes more disordered entropy
increases
you have a full jar of marbles. when you tip the jar over all of the marbles roll away. you would not expect the marbles to spontaneously order themselves back into the jar because
processes in which disorderly states tend toward orderly states are improbable and simply not observed
make up three examples to illustrate that natural systems tend to proceed toward greater entropy
run down house, campfire, free expansion of gas
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 into contact. suppose the cooler block cools to 5 degrees C and the warmer block warms to 25 degrees C. this would violate the
second law of thermodynamics
what does it mean to say that energy becomes less organized when it transforms from one form to another
the quality of energy is lowered
Systems left alone tend to move to a state of greater entropy
true
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
when work is done by a system on something else the temperature of the system decreases
true
whenever heat is added to a system it transformed to an equal amount of some other form of energy
true
running a refrigerator with its door open in a hot room makes the room
warmer
