5.8. The law of conservation of moment of momentum

From the basic equation of the dynamics of rotational motion, it follows that

For a closed (isolated) system, the resulting moment vector all external forces acting on the body is zero and

or

This statement is the content of the law of conservation of angular momentum: and is formulated as follows: if the resulting moment of all external forces with respect to the fixed rotation of the body is zero, then the angular momentum with respect to this axis does not change during movement. This law can be generalized to any unclosed system of bodies, if the resulting moment of all external forces applied to the system relative to any fixed axis is identically zero, then the angular momentum of the system relative to the same axis does not change over time.