Here there's an expansion going on, so the system is doing work to the external world.

这里发生了膨胀,所以系统对外界做功，活塞被推出来。

麻省理工公开课 - 热力学与动力学课程节选

And I have this adiabatic expansion where p external is really small.

这时的情况,跟理想气体的。

麻省理工公开课 - 热力学与动力学课程节选

p We want p equal to p external for the entire expansion, p2 and p external is decreased steadily from p1 to p2.

在膨胀过程中保持p等于外部，外部p很快从p1衰减到。

麻省理工公开课 - 热力学与动力学课程节选

So that's going to results in an expansion where the new volume new temperature new pressure and an external pressure, p2 which is p2 which is a smaller pressure.

这样经过膨胀,到达了,状态为V2，T2，p2的末态，外界压强也降低到。

麻省理工公开课 - 热力学与动力学课程节选