Question

Compute the efficiency of the heat engine shown in Fig. 1. The engine uses a rubber band mass M whose equation of state is of T alT where Tis the tension, I is the rubber band length per unit mass (inverse linear density, L MI) and T is the temperature. The specific heat (heat capacity per unit mass) is a constant c c. (For this problem you can assume that J dU = Mfa(T)dT for processes at constant AND for processes at constant T. The proof that this is true will come in block 3) Hints: First identify what parts of the cycles (if any) are isothermal and use that to find the relationship between the temperatures TA, Th and Te at the three different points in the cycle and the other state variables of the system. Remember that by definition S 2To a TO C b lo 210

Answer 1

Solution Ag, ^haan Figune the engre epadion whore ubben hand q* ma M Tension, mars C teuporchse 3pecfie heat Capac figwe CtC (30thomal padh a- digune Also d'nom egpotion 7a & nd T Cofont dhom eetond Fhom Con wite Te T Olo Tc 2.OlD To fitcat acdd fn b) MoTo d MAo 2 r1Tolo MC To CRa-c Heast odded n -sb cab M 7olu HC CTo C Ta 2- olo 2 M7olo MIolo W 3M7lo