Well, the change in f is the value of f at the upper point here, which is x0+delta x, and minus its value at the lower point P, which is f of x0, divided by delta x.

f的变量就是f在上面的点时的值， x0+delta x，减去f在下面的点P时的值，x0，再除以delta x。

youdao

It's not constant pressure, because we have a delta p going on. It's not constant volume either.

也不是恒容，这个限制,是这个实验的限制。

麻省理工公开课 - 热力学与动力学课程节选

It's tabulated in books, and this we can measure p in the experiment. Delta p here is the change in pressure from the left side to the right side, and we can put a thermometer, measure the temperature before the experiment and measure the temperature after the experiment.

这列在书上，这个量我们在,实验中也可以测量，在这里Δ,是从左边到右边的压强变化，我们可以放一个温度计，去测量实验前的温度,再去测量试验后的温度。

麻省理工公开课 - 热力学与动力学课程节选

And so they defined them, p after many experiments, the limit of this 0 delta T delta p and the limit of delta p goes to zero as the Joule-Thomson coefficient.

他们定义了这些量，以及它们的范围，ΔT比Δ,Δp的极限趋近于,叫做焦耳-汤姆逊系数。

麻省理工公开课 - 热力学与动力学课程节选

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