A gas is enclosed in a cylinder fitted with a light frictionless piston and maintained at atmospheric pressure.

A gas is enclosed in a cylinder fitted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is observed to increase slowly from 12.0 to 18.2 Calculate (a) the work done by the gas and (b) the change in internal energy of the gas.