We'll then look at the quantity, internal energy, which we define through the first law, and we think of it as a function of two variables T and V.

接下来我们考虑内能，这是由热力学第一定律定义的物理量，我们把它看作T和V的函数。

麻省理工公开课 - 热力学与动力学课程节选

In other words, u is a function of T and V.

话句话说，u是T和V的函数。

麻省理工公开课 - 热力学与动力学课程节选

Now, I hope you guys know that much calculus, that when you take a derivative of a function of a function, namely v square over 2 is a function of v, and v itself is a function of t, then the rule for taking the derivative is first take the v derivative of this object, then take the d by dt of t, which is this one.

我希望你们了解更多的微积分知识,当你对复合函数求导时,也就是说v^/2是关于v的函数,而v本身是关于t的函数,求导的法则应该是,第一步是这一部分对v求导,然后v再对t求导,得到这一部分

耶鲁公开课 - 基础物理课程节选