The [[derivative]] of angular momentum with respect to time is equal to the sum of the external moments ('''r''' x '''F''') applied to the system. From this, it can be concluded that in the absence of an external moment, angular momentum must be conserved. | The [[derivative]] of angular momentum with respect to time is equal to the sum of the external moments ('''r''' x '''F''') applied to the system. From this, it can be concluded that in the absence of an external moment, angular momentum must be conserved. |