S = $ + cheln ,LJ (2 - L.) = cLIn U b U. 2(L) L ? (3.62) A rubber band's fundamental relation is given by (3.62) in Callen. (a). Starting from the fundamental relation, express U in terms of the temperature T. (b). Find the change in internal energy obtained by adiabatically stretching the rubber band by dL. How is this related to the tension and work done in this process