We all have an intuitive notion of velocity right now.

我们现在都有一个对速度的直观概念

耶鲁公开课 - 基础物理课程节选

So, the two most elementary ideas you learn are what is the average velocity of an object, as then ordered by the symbol v-bar.

你们学过的两个最基本的概念是,物体的平均速度,用"v拔"表示

耶鲁公开课 - 基础物理课程节选

But before you even do that, I want to define for you an important concept, which is the velocity at a given time, v .

但在这之前,我要给你们定义一个重要的概念,也就是给定时刻的瞬时速度v

耶鲁公开课 - 基础物理课程节选