4) Thermodynamics of the rubber band is represented by the first Law of thermodynamics as E(S,V,L) where L is the length of extension at applied force f. The incremental change in the internal energy is given as dE=TdSpdV+fdL a. We are interested in experiments at constant T,P. What would be ou new thermodynamic potential? b. Using the new thermodynamic potential show that the change in entropy with respect to extension can be obtained by just measuring retraction force f in different temperatures: (LS)T,P=(Tf)P,L