How is angular momentum conserved?

Angular momentum is a property of rotating bodies that depends on the distribution of mass and the velocity of that mass in relation to an axis of rotation. The principle of conservation of angular momentum states that if no external torques act on a system, the total angular momentum of that system remains constant.

When external torques are absent, the rotational motion of a system, or the sum of the angular momentums of its components, does not change. This principle can be observed in scenarios such as a figure skater pulling in their arms to spin faster: the angular momentum remains the same, but the distribution changes.

In contrast, when external torques are present, they create a change in angular momentum, causing it to increase or decrease depending on the direction and magnitude of the torque applied. Thus, the conservation of angular momentum clearly hinges on the absence of these external influences. This principle applies universally, making it a consistent rule across a variety of physical situations.