1. The problem statement, all variables and given/known data Isothermal process! I have a cylinder with base area of 0.01m^2. I have a piston that is 0.1 meters from the bottom giving a volume of 0.001m^3. I have a weight of 1500 Newtons. This gives a pressure of 1.5E5 Pa. Now, I remove 500 Newtons and the piston moves upwards. Volume increases, pressure decreases. What is the work done by the gas on the weight as the piston moves upwards? 2. Relevant equations PV = PV, work = Force X distance, Work = (PV)ln(V2/V1) 3. The attempt at a solution See attached solution. Method 1 gives me 50 Joules of work, Method 2 gives 60 Joules of work. Where am I making a mistake? Both methods seem OK to me.