On the left is a simulation of a free floating piston with 40 gas molecules underneath. A graph of the volume under the piston and the temperature (average kinetic energy) is above. The acceleration of gravity has been decreased to make the simulation a bit slower. There is slight damping on the piston so that if you wait long enough the oscillations of the volume and temperature will gradually level off.
The piston is initially allowed to fall from near the top of the container under the influence of gravity. Which color on the graph corresponds to temperature and which color corresponds to volume? ('Reset' will start the initial simulation over.)
As the piston falls, the average kinetic energy of the molecules (the temperature) increases. Where does the energy for this come from?
At what point in the cycle is the pressure a maximum? A minimum? (Hint: Think about the ideal gas law.)
Click on each of the following temperature cases and wait 20 time units (Note: The time part of the graph does not start over.). Record the average volume (halfway between the max and the minimum) in each case. What can you say about the relationship between temperature and volume?
In the first simulation the temperature goes up initially but in the other simulations the temperature goes down initially. Explain why this happens.