The common definition of heat is "the energy transfered from one body to another one as result of a temperature difference" This energy isn't "in" any of the bodys, rather it's "energy on the move" between the two. But if energy is the potential to do work, then heat is the potential of what to do work? (for example, KE is the potential of the body that's moving to do work.) I think that it's the potential of a system of bodies with different temperatures to do work. Is that right? Thanks.