What's happening and interests me acoustically, and again we'll come back to it, is that we're getting up toward here, and notice how these pitches in terms of the ratio frequencies are getting very close together.

这段乐曲从声学的角度上让我很感兴趣,我们再看看它,音乐升高到这里,然后我们注意到这些音高,是如何根据频率比最后汇合在一起的

耶鲁公开课 - 聆听音乐课程节选

That is the whole triumph of calculus is to know that by looking at the position now, the position slightly later and taking the ratio and bringing later as close as possible to right now, we define a quantity that we can say is the velocity at this instant.

这就得靠微积分了,通过了解它现在的位置,和一小段时间以后的位置,计算它们的比,再让时间间隔尽可能缩短,我们就定义了一个,被我们称之为瞬时速度的物理量

耶鲁公开课 - 基础物理课程节选