在书上练习的一道题目 a rubber band are used as a basis for a heat pump. it is claimed that under adiabatic conditions, a rather large (1kg) rubber band requires 14kj of work to stretch from its original lentgh L1= 1m to a final length of L2=5m. the stretching process will cause the polymer to cool from initial temperature 300Kto final temperature 250K. the tension force of the rubber band as a function of temperature and length is F=A/T*(L-L1), where A=1000 kJ*K/m^2. The specific heat capacity of the polymer, valid for its unstretched state, is CL1=1kJ/(Kg*K). Evaluate whether the descirbed process is thermodynamically possible, by a rigorous examination of all thermodynamic constraints. 请问版上的高手，这题该怎麽着手比较好 目前知道是 irrevisible. du=dQ+dW, du=Tds-pdv, du=cvdT+(T(dp/dT)-P)dv 要如何知道是热力学上可能的? 只知道-pdv=F*dl, 我卡在du展开的第二项，T没法积分 会的P币500 --

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