The law that the total amount of angular momentum in a system remains the same (in the absence of any force not directed toward or away from the point or axis about which the angular momentum is referred).
The scientific law that states no angular momentum can appear out of nowhere or disappear
As the centre mass of a rotating body moves closer to the axis of rotation, the velocity of the body increases. This law is demonstrated very vividly by ice skaters when they start to rotate and then pull their arms in to their chest. Search for physics books on Amazon.co.uk
when the net external torque on a system is zero, angular momentum of that system remains constant
when an object or system of objects has no net outside forces acting on it, the total amount of its angular momentum does not change.
The principle that absolute angular momentum is a property that cannot be created or destroyed but can only be transferred from one physical system to another through the agency of a net torque on the system. As a consequence, the absolute angular momentum of an isolated physical system remains constant. The principle of conservation of angular momentum can be derived from Newton's second law of motion.
If the net torque acting on a rigid body is zero, then the angular momentum of the body is constant or conserved.
