Repeat the above problem for the case where the heat is added and removed under conditions of constant length.
Heating a stretched rubber band increases its tension, making it tend to contract, and a contracting rubber band tends to cool off. You are invited to design an engine that does work by pulling rather than pushing. You will need a hot reservoir, a cold reservoir, and a rubber band with one end fixed and one attached to a movable piston. Suppose that the heat addition and removal are done isothermally (e.g., the system is immersed in reservoirs as appropriate). Sketch and label the four parts of the cycle for this engine, and also sketch and label the four parts on a F-L diagram, which is like a p-V diagram, except using tension (- F) and length (L). (Note that the work done is d W= - FdL, because the system is pulling, not pushing.)