Question

A gas is contained in a chamber, as indicated in the figure below. Suppose the region

outside the chamber is evacuated and the total mass of the block and the movable

piston is 135 kg. When 2050 J of heat flows into the gas, the internal energy of the gas

increases by 1730 J. Calculate is the distance s through which the piston rises.

Answer 1

The work done is

$$W=Q-\Delta U.$$

On the other hand, it is

$$W=mgh.$$

Thus:

$$mgh=Q-\Delta U,\\ h=\frac{Q-\Delta U}{mg}=\frac{2050-1730}{135\cdot9.8}=0.24\text{ m}.$$