Hi all Working through a past paper as I have an exam tomorrow and can't quite see where to start with the following question. 1. The problem statement, all variables and given/known data A steam engine produces 2.4 kJ of work per cycle for a heat input of 6 kJ. If the temperature of the hot source for the engine is 600 °C and the temperature of the cold sink is 100°C, what is the maximum possible efficiency of the engine? 2. Relevant equations The only equations I can think of relating to this question involve other variables that aren't given. My initial thought was that as we're finding the efficiency any unknown values will cancel each other out, but I don't seem to get anywhere. Could somebody please point me in the direction of what equation I should be looking at? The annoying thing is it's only a 2 mark question! Thanks in advance.