aU aU SU aS(op/δ=76S-p6V 6S+ a-U 8S8v+ aU aU 6U=a2(S)2+ δ6S+ aVas aSap 2(6)2 aT aT (δS)2+ 6SδV S (δV) aS aS =δ7oS-6pδv △S=△S △U+P0△ <0 8sx8U+zδV 0(0-7)S-(P-p)=0 热平衡条件7=T力平衡条件|=PV T S p V V U S S U U V S δ δ  δ = δ − δ         +        = T S p V V V p V S S p S V V T S S T V V U V S S V U S V V S U S S U U V S V S δ δ δ δ (δ ) δ δ δ δ (δ ) δ (δ ) δ δ δ δ (δ ) 2 2 2 2 2 2 2 2 2 2 2 = −          −         −         +        =   +    +    +   = 0 δ δ δ ~ δ 0 0 = + = − T U p V S S (T0 −T)δS −(p0 − p)δV = 0 热平衡条件 T = T0 力平衡条件 0 p = p 0 Δ Δ Δ ~ Δ 0 0  + = − T U p V S S