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

What is it you have to know about this object that was thrown, I claim, is the initial location of the object and the initial velocity.

关于这个物体,我们需要了解什么,我要强调的,就是这个物体的初位置和初速度

耶鲁公开课 - 基础物理课程节选

Now, a little later, and a little later later, because between the first and second, you get a velocity, the second and third you get another velocity.

现在,再晚一点,再再晚一点,因为第一个和第二个位置,你得到一个速度,第二个和第三个位置,你得到另一个速度

耶鲁公开课 - 基础物理课程节选