Particle's moving in a plane.

物体在平面内运动

耶鲁公开课 - 基础物理课程节选

Then, I gave you one other very important example of a particle moving in the x-y plane.

下面我再拿一个重要的例子,质点在 x-y 平面内的运动

耶鲁公开课 - 基础物理课程节选

Our picture now is going to be some particle that's traveling in the x-y plane.

我们现在的情景是在 x-y 平面内,运动的质点

耶鲁公开课 - 基础物理课程节选

And that's the following. Let's take a particle that is moving in the x-y plane, so that at one instance-- sorry, let me change this graph-- is here--oh, this is bad.

接下来,我们来看一个物体,在 x-y 平面内运动,在这个例子中,对不起,我要重画一下这个图,在这里,这画得不好

耶鲁公开课 - 基础物理课程节选