The work dW PSal Pdy m-w-北Pa P↑ (PA VATA) The work done by the gas is equivalent to (PB:VB>TB) area under the PV curve. VB The work S P dl (PB ,VB ,TB ) P (PA,VA,TA) O dV V The work done by the gas is equivalent to area under the PV curve。 VA VB