If you connect the body to a spring, which is neither compressed nor extended, there's no force acting on it.

如果将一个弹簧连在这个物体上,弹簧既没有被压缩也没有被拉伸,也不会有力作用在它上面

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The spring is getting squashed because you are pushing down and the floor is pushing up.

弹簧现在被压缩了,因为你在往下压,地面在往上推

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If it's positive, it means you've stretched it, if it's negative, it means compressed.

如果它为正值,就说明弹簧被拉伸了,如果它为负值,就说明弹簧被压缩了

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Therefore, it'll compress by an unknown x, which is equal to mg divided by the force constant of the spring.

因此它的压缩量为 x,也就等于 mg 除以弹簧的弹性系数

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This equation is telling you if you compress it, namely if x is negative, F will be then positive, because it's pushing you outwards.

这个方程告诉我们,如果压缩弹簧,即令 x 为负,F 就为正,因为推力的方向向外

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It also tells you that if you compress the spring, compress it means x is now-- x is measured from this position, where the spring is neither compressed nor expanded.

它还能告诉你,如果压缩弹簧,压缩就意味着现在 x...,x 是从这个位置开始算的,在这个位置弹簧既没有压缩也没有伸长

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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

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