Because any velocity I ascribe to a particle or an object, you will add a certain constant to it by the law of composition of velocity.

因为我描述的任何一个质点或者物体的速度,你都要根据速度叠加法则,给它加上某个常数

耶鲁公开课 - 基础物理课程节选

You want to know how fast the guy is moving.

你们想知道这个质点的速度有多快

耶鲁公开课 - 基础物理课程节选

A clock tells you what time it is, but you can also say what time it is by seeing how fast the particle is moving because you know it started with some speed.

时钟能告诉你现在的时间,但你也可以通过测量质点速度,来判断当前的时间,因为你知道它的初速度

耶鲁公开课 - 基础物理课程节选

How fast is this particle moving?

那么这个质点的速度是多少

耶鲁公开课 - 基础物理课程节选