1. The problem statement, all variables and given/known data a) There is a piston-cylinder arrangement; initial pressure is 200 kPa, initial volume is 0.04m^3. Volume of the gas increases to 0.1 m3 while the pressure remains constant, ie a constant pressure process. Calculate the work. b) There is a piston-cylinder arrangement; initial pressure is 200 kPa, initial volume is 0.04m^3. Volume increases to 0.1 m3 while its temperature is constant, ie a constant temperature process. c) There is a piston-cylinder arrangement; initial pressure is 200 kPa, initial volume is 0.04m^3. Final volume is 0.1 m3 but this time PV^1.3=constant during the process ie a polytropic process with n=1.3. My question is: 1) Does constant pressure process always give the biggest work? 2) What polytropic exponent gives the biggest work? 3) What would be the case for a isentropic process with the same final volume? 4) How can we understand if the energy of the system increases or decreases, taking the gas as a system? 2. Relevant equations 1) dw=Pdv; P1V1^n=P2V2^n 3. The attempt at a solution 1) 1) as you can see from the picture that constant pressure gives the biggest work, but I cannot be sure if it is always so? 2) if 1 is correct analyse then the answer to 2 should be polytropic exponent is 0. 3) I do not know this now but let me wait for it. I can answer it later. 4) I am not sure if this can be determined because we do not know what energy is given to the system so that we could use the equation Q-W=ΔE http://home.iitk.ac.in/~suller/lectures/lec5.htm Thank you.