在書上練習的一道題目
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.
請問版上的高手，這題該怎麼著手比較好
目前知道是 irrevisible. du=dQ+dW, du=Tds-pdv, du=cvdT+(T(dp/dT)-P)dv
要如何知道是熱力學上可能的? 只知道-pdv=F*dl, 我卡在du展開的第二項，T沒法積分
會的P幣500
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