And if you work out the energetics as we've gone with thermochemistry, dH you discover there's a huge negative delta H.

如果你计算能量变化,就像在化学热力学中所作的一样，你会发现很大的负的。

麻省理工公开课 - 热力学与动力学课程节选

Delta v is positive in this direction here, the work is negative. So work on the system is positive. Work done by the system is negative.

功是负的，总而言之,外界对系统做功的符号为正。

麻省理工公开课 - 热力学与动力学课程节选

And so, in fact, the delta here is negative.

因此，实际上这里的delta，E是负的。

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So delta u of reaction is approximately equal T to negative Cv for the calorimeter times delta T.

所以反应的ΔU近似等于,负的量热计的Cv乘以Δ

麻省理工公开课 - 热力学与动力学课程节选

So if delta v is negative, in this case delta v is negative, OK, delta v is negative, pressure is a positive number, negative times negative is positive, work is greater than zero.

也就是当活塞,压缩气体的时候，做的功是正的，按照这一规定,我们需要在这里，加上一个负号，这是习惯规定。

麻省理工公开课 - 热力学与动力学课程节选

Delta v is going to be negative. w is going to be negative. Sorry, I got it backwards again.

这样就对外界做了功,这时候ΔV是正的。

麻省理工公开课 - 热力学与动力学课程节选