Re: [問題] 絕熱可逆的功
※ 引述《ohmygod0715 (Thomas)》之銘言:
: 從書上看內能 = 功 = Cv(T2-T1) = (1/1-r)(P2V2-P1V1)
: 想請問(1/1-r)(P2V2-P1V1) 是怎麼導出來的Orz...
PV = nRT
VdP + PdV = nRdT
又PV^r = const
=> rPV^(r-1)dV + V^r dP = 0
=> rPdV + VdP = 0
=> rPdV + nRdT - PdV = 0
=> (1-r)PdV = nRdT = d(PV)
S: 積分
U = S CvdT = Cv(T2-T1) = W = S PdV = [1/(1-r)]S d(PV)
= [1/(1-r)][P2V2 - P1V1]
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