Two identical bodies of constant heat capacity which are at temperatures T1 and T2 respectively are used as reservoirs for a heat engine. If the bodies remain at constant pressure and undergo no change of phase determine the work obtainable from the engine when both reservoirs attain a final temperature equal to Tf . What is the condition for the work obtainable to be a maximum internal energy and enthalpy of the air for each of the processes. Sketch the path followed by each of the processes on a single diagram