1. The amount of heat that an engine rejects to the cold reservoir is 3 times the amount of work that it does. What is the efficiency of the engine? e = W/ Qh = 1 - Qc/Qh For this problem, I said e= w/3w. Thus e would equal 1/3 = 0.333. This however is not correct. What did I do wrong? 2. A Carnot engine operates between the temperatures 390 K and 300 K. How much heat is discarded for the engine to produce 1900 J of work? e = 1 - Tc/Th e = 1 - 300K/390K = 0.2307 e = W / Qh thus 0.2307 = 1900J/ Qh I solved for Qh and i got the answer to be 8233.3 J This isn't correct either, but I'm not sure what I'm doing wrong. 3. During each cycle a reversible engine absorbs 1550 J of heat from a high-temperature reservoir and performs 1200 J of work. How much heat is exhausted to the low-temperature reservoir during each cycle? Qh = W + Qc 1550 = 1200 + Qc and then I solved for Qc. This isn't correct either. Please Help! I am desperate and I really don't understand these problems.