Wiki上质心的定义和性质：“In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may be applied to cause a linear acceleration without an angular acceleration.”

反证法之
假设相对静止的系统有多于一个质心，那么我可以任选两个Ca，Cb，以它们为端点作一线段AB，令AB中点为O.以O为中心，A，B两点加非零力偶,则系统将产生角加速度，与上面引文相违背。
【 在 Hihere001 的大作中提到: 】
: 别吹啊，请用事实说话。
: 请你证明“一个N质点系统的质心的唯一性”
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