gas in a cylinder with a moveable piston expands from 0.255 L to 0.892 L
against a constant external pressure of 0.987 atm. In this process, the
piston cools from 23.5°C to 22.6°C. What is the total change in internal
energy for the system (gas in cylinder)? Assume the specific heat capacity
of the piston is 0.88 J/g.°C and it has a mass of 1.25 kg.