And in particular let's look at, for example, du/dV du/dV at constant temperature.
更特殊一点考察,恒定温度下的。
p Well, it's not just p dS/dV because there's some dS/dV at constant T.
它不是简单的,因为式子中还包含,恒定温度下的。
Now, we can immediately see what du/dV at constant entropy is.
我们能够很容易看出,恒定熵的条件下du/dV的数值。
du/dV at constant T. And so, what is it?
求恒定温度下的du/dV,但是,这个量是什么?
It's constant pressure. OK, so now, last time you looked at the Joule expansion to teach you how to relate derivatives like du/dV.
这是恒压的,好,上节课你们,学习了焦耳定律,以及怎样进行导数间的变换。
dS/dV And that, now, we know must equal dS/dV, with a positive sign. At constant temperature.
我们知道这个等于恒定温度下的,符号为正。
dV dT Is equal to minus dV/dT at constant pressure.
它等于,负的恒定压强下的。
dS/dV There's some variation, dS/dV, at constant temperature.
这里有一点变化,即恒定温度下的。
p So dV/dT at constant pressure is just nR over p.
所以恒定压强下dV/dT等于nR除以。
V So it's minus T dV/dT at constant p, plus V.
负的T乘以恒定压强下dV/dT,再加上。
du/dV So now our du/dV, dp/dT at constant T is just T times dp/dT which is just p over T minus p, it's zero.
现在我们的恒定温度下的,等于T乘以dp/dT,在这里,等于p除以T,最后再减去p,结果是0。
p dA/dV, at constant T, must be negative p.
在恒定温度下,dA/dV等于。
The dA/dV is calculated at constant temperature.
就像这样,dA/dV是在恒定温度下的偏导数。
OK, so for a constant volume process, du we can write du, partial derivative of dT u with respect to T at constant V, dT, dv plus partial derivative of u at constant V, dV.
好,对于一个恒定体积的过程,我们可以写出,等于偏u偏T,V不变,加上偏u偏V,T不变。
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