A gas has its pressure reduced while its volume is kept constant. What does
this look like on a PV diagram?
a horizontal line going to the right
a horizontal line going to the left
a vertical line going up
a vertical line going down
How did the temperature of the gas change during that process?
the temperature increased
the temperature decreased
the temperature stayed the same
the temperature change cannot be determined
from the information given
The second law of thermodynamics says for a heat engine:
You get more work energy out than you put in as heat
You get the same work energy out as you put in as heat
You get less work energy out than you put in as heat
Ralph is confused because he knows that when you
compress gases, they tend to heat up. Think of bicycle pumps, for example:
compressing the air heats up the nozzle of the pump. Yet section 12.3 (8th
edition) talks about "isothermal" processes where the temperature doesn't change. How are
such processes possible? How can you compress a gas without its temperature
Just take away some heat at the same time, by (for example) surrounding the gas with something cold.