You can ask me where it will be nine seconds from now, eight seconds from now, how fast will it be moving.

你们可以问我九秒后它的位置,或者八秒后,以及它的运动速度

耶鲁公开课 - 基础物理课程节选

For example, if you're talking about the chalk--if I throw the chalk, you will have to know where it is and how fast it's moving.

比如说,这支粉笔,如果我扔出这支粉笔,你就像知道它的位置和速度

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

If you want to know how fast it's moving at a given time, if you want to know the velocity, I just take the derivative of this answer, which is 10-10t.

如果你想知道它在给定时刻的运动有多快,如果你想知道它的速度,我只要对这个式子求导,得到10-10t

耶鲁公开课 - 基础物理课程节选