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

When you have a velocity in the moving plane frame and you want to find the velocity on the ground, you should add to every object in the plane the velocity of the plane with respect to the ground.

当你在运动的飞机上运动,然后你想找到相对于地面的速度,你就应该给每个物体加上,飞机相对于地面的速度

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

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