So you should know when you look at a graph like this what it's doing.

因此当你看到这样一个图表时,要知道它是怎样运动的

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Or a football player--when you're running down the field, why did you go to this way instead of that way ? when you're running down the field?

或者是问一个橄榄球运动员--当你在操场上奔跑时，你为什么要往这边跑而不是那边呢,当你在操场上跑的时候？

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It means, when you are accelerating upwards, as the elevator picks up speed, the reading on the spring will be more and you will feel heavy.

也就是说当你向上做加速运动时,就像电梯加速的时候,弹簧的读数会增大,你会觉得自己变重了

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The fact that when you go in a circle, you accelerate is what we're learning here, coming from the fact that velocity is a vector and its change can be due to change in the magnitude or change in direction.

而当你做圆周运动时你也在加速,这是我们在这里所学到的,原因就在于,速度是一个矢量,其变化可以通过改变模长,或者方向来实现

耶鲁公开课 - 基础物理课程节选

It tells you when a particle moves in a circle, it has an acceleration in a negative R direction, namely directed towards the center.

它告诉你当一个物体在圆周上运动时,它有一个在 -R 方向的加速度,也就是说是直接指向圆心的

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