Thermodynamics!
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 be cool
false
If all the friction could be eliminated in a heat engine, its efficiency would be 100%.
false
In buildings that are electrically heated, turning the lights on
doesn't waste energy
The first law of thermodynamics is a restatement of the
conservation of energy
Entropy measures
messiness
Systems that are left alone, tend to move toward a state of
more entropy
what does it mean to say that energy becomes less organized when it transforms form one form to another
It means that it is the only process that can result in an increase in entropy. To have greater entropy there must be lower energy.
How does the second law of thermodynamics relate to the direction of heat flow
It states that heat flows from a hot source to a cold source
The greater the difference in temperature between the input reservoir and output reservoir for a heat engine, the
greater the efficiency
An absolute temperature of 110K is the same as what celsius temperature
-163C
The lowest possible temperature in nature is
-273 degrees Celsius
An absolute temperature of 47K is the same as what celsius temperature
200C
80 joules of heat is added to a system that performs 55 Joules of work. The internal energy change of the system is
25J ( 55=80-Qc) Qh-Qc=work
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 about
273 degrees C
At what temperature would molecules of gas have twice the average kinetic energy they have at 26C room temperature
325C
Calculate the ideal efficiency of a power plant that runs between temperatures 400K and 150K
63%
The temperature of an object is raised by 70C This is equivalent to what increase in its absolute temperature
70
There is a type of power plant known as OTEC that operates on the temperature of difference between warm surface waters and cool deep waters. what is the Carnot efficiency of such a power plant if the surface water is 25C and the deep water is 4c
84%
The ideal efficiency for a heat engine operating between temperatures of 2700 K and 300 K is
85% ( 2050-310=1740/2050=84.5 X 100)
Make up three examples to illustrate that natural systems tend to proceed toward greater entropy
An abandon house, burning campfire, cream spreading in coffee
Adiabatic process occur in
Earths mantel, the oceans, the atmosphere ( all of the above)
Ceramic automobile engines that operate at higher temperatures will be
More efficient
You have a jar full 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
Process in which disorderly states tend toward orderly states are improbable and simply not observed.
When mechanical work is done on a system, there can be an increase in its
Temperature and internal energy ( both of the above)
distinguish between the first and second laws of thermodynamics in terms of whether or not exceptions occur
The first law has no exceptions, simply states that you can't lose or gain any energy than what you had, the 2nd law says actually the only way to have 100% efficiency is to be at 0k
It is possible to totally convert a given amount of mechanical energy into heat
True
If the internal energy of a volume of air at 10C is doubled, its temperature will then be 20C
false
It is impossible to wholly convert a given amount of heat energy into mechanical energy
false
Pull a closed plastic bag of dry air quickly down from a high elevation and the bag of air will become
hotter
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
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
Give two reasons why a tire pump becomes hotter when used to pump a tire
its energy is increased and there is external work done on it.
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 warmer block warms to 25 degrees C. This would violate the
second law of thermodynamics
Efficiency in a heat engine is increased when there is a greater difference in input and output temperatures
true
Systems left alone tend to move to a state of greater entropy
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 transforms to an equal amount of some other form of energy.
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 ( both A and B)
Running a refrigerator with its door open in a hot room makes the room
warmer