Right, I might be dumb, or whatever, but i've pondering for a while and it's annoying because I feel like there is not enough information (too many unknowns not enough equations) 1. The problem statement, all variables and given/known data The piston/cylinder arrangement shown Fig Q3 contains air at a pressure of 2 bar and a temperature of 450 ºC. The air is allowed to cool to an ambient temperature of 18ºC. (a) Is the piston resting on the stoppers when the system reaches its final state? [Show all working] (b) What is the final pressure in the cylinder? (c) If the cross-sectional area of the piston/cylinder is 2 m^2,calculate the work transfer during the process. Fig 3 is a simple piston/cylinder, 2m in length with stoppers at 1m. 2. Relevant equations The properties of air may be related to one another by the equation pV = mRT where, p = pressure; V = volume; m = mass; R = specific gas constant; and T = temperature. W = -pdV, assuming isobaric. W= pvln(v1/v2) - assuming isothermal, which it isn't. 3. The attempt at a solution Not told whether the process is isobaric or not. Clearly it is not isothermal and isometric/choric up UNTIL AND IF the piston rests on the stoppers. So, is it REASONABLE to assume that this process is isobaric? The second question asks the final pressure, which make me hesitate whether isobaric is applicable in this case. Could a process be non isobaric, non isothermal, non isochoric at the same time? (I don't know why not, but just in case). If Isobaric - simply P1V1/T1 = P2V2/T2 where P1=P2 From that you can find that V ~ 1.6m^3 A is constant 2m^2, so L = 0.8 BUT the stoppers are at 1m. The piston stop at the stoppers, temperature keeps dropping, shouldn't this affect pressure? Would it then be reasonable to split the process into 2 processes? One before it reaches the piston, and then the second after? Or is there some other way?