The momentum of the cluster as a whole would not change if there are no external forces on the system, 0 if the net sum, the total external force, is zero.
星云的动量,作为整体是不变的,若无外力作用于系统,如果外力总和为。
The momentum of the cluster as a whole would not change if there are no external forces on the system, 0 if the net sum, the total external force, is zero.
星云的动量,作为整体是不变的,若无外力作用于系统,如果外力总和为。
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