1. The problem statement, all variables and given/known data A heat engine using 110g of helium as the working substance follows the cycle shown in the figure. http://session.masteringphysics.com/problemAsset/1074114/5/19.P59.jpg What is the engine's thermal efficiency? 2. Relevant equations n=W/Q_h 3. The attempt at a solution Alright so up to this point I have figured out p1,p2,p3, T1,T2,T3, V1,V2, and V3. I tried doing W = area of triangle = .5(5-1)atm*(5.0*10^-3-1.0*10^-3)m^3 and got .008J. I assumed Q_h was 2200K because that is what I got for the temperature between T2 and T3, and that is where the heat should be going in. So I divided and 36.36% but that is wrong. Any help here? Thanks!