1. Statement of the Problem One mole of a monatomic ideal gas is taken through the reversible cycle shown. Process bc is an adiabatic expansion, with P_b = 10.0 atm and V_b = 1.00E-3 m^3. Find a) the energy added to the gas as heat, b) the energy leaving the gas as heat, c) the net work done by the gas, and d) the efficiency of the cycle. Here is a picture of the problem, with the figure (it is problem #7): http://www.pa.msu.edu/courses/PHY215/handouts/HW3.pdf" [Broken] 2. Relevant equations I honestly don't even know which equations are relevant at this point, beyond the First Law of Thermodynamics and the Ideal Gas Law. I believe I have incorporated every equation in lectures and the book and gotten nowhere. 3. The attempt at a solution Since it is a monatomic ideal gas, I'm assuming that the ratio of specific heats (gamma) is 1.66. Then I use the fact that P*V^gamma = constant for adiabatic processes to solve for P_c (since I already know the values of P_b, V_b, and V_c). From here I can calculate P, V, and T for each of the 3 states of the problem. I'm not sure I need all this information, but I have it in case I do need it. To find the net work done by the gas over the cycle, I used the following equation for net work done over an adiabatic process: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/adiab.gif By the First Law of Thermodynamics this would also give me the opposite of the internal energy change on the path bc. Beyond this, I have no idea. My trouble is that I don't know when/how heat is entering the system and when/how it is leaving the system, except that I know that no heat is exchanged during the adiabatic portion of the cycle (path bc). This problem seems straightforward but there is a key piece of logic that I'm missing! Can somebody help me out?