# (Hopefully) simple thermodynamics question

1. Sep 13, 2010

### AxiomOfChoice

Suppose you have a piston of ideal gas that's thermally isolated from its surroundings. You compress the gas by pushing down on the piston. Question: Does the temperature of the gas change, and why?

My answer: YES, it changes. Since $\Delta U = Q + W$, and work was done ON the gas (by compressing it), $\Delta U > 0$. Since the energy of an ideal gas is only dependent on the temperature of the gas, this implies $\Delta T > 0$.

2. Sep 13, 2010