,在y的负方向,那么也有一个常力,在y的正方向,这两个力互相抵消。
in the minus y direction and there is a normal force in the plus y direction and these two exactly cancel each other.
,在y的负方向,那么也有一个常力,在y的正方向,这两个力互相抵消。
in the minus y direction and there is a normal force in the plus y direction and these two exactly cancel each other.
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