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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We're going to ask, "What's the needle showing at different times?"

我们想要知道,"不同情况下指针的读数是多少"

耶鲁公开课 - 基础物理课程节选

You feel heavy and it reads more because the poor spring not only has to support you from falling through the floor, but also accelerate you counter to what gravity wants to do.

你感到自己变重以及读数增加,因为现在弹簧不仅要支撑你,不让你掉下来,还要抵消重力的作用让你加速

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But if I'm accelerating, the force exerted by the spring and therefore, the needle the weighing machine reads is m.

但是如果我在加速运动,那么弹簧的弹力,也就是称重机上指针的读数就是 m

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When I was not accelerating and everything was at rest, ma was 0, w was mg, and w was the reading on the needle.

当我还没有加速,一切静止的时候,ma 是 0,w 就等于 mg,w 就是指针的读数

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This spring is getting squashed on either side, and it'll squash by certain amount x, that depends on your mass, and that x will be turned into a motion of a needle and that'll read your mass.

这个弹簧两边都会受到压缩,压缩量为 x,它由你的质量决定,x 会转换成指针的运动,你从而可以读数

耶鲁公开课 - 基础物理课程节选