The angular momentum of a moving body remains constant, if

The angular momentum of a moving body remains unchanged unless an external torque is exerted on the moving body. Angular momentum denotes rotational motion around the axis in any object depending upon its distribution of mass and rotation velocity. By principle, there would be a lack of a change in time with respect to total angular momentum when no torque external to a system is given to it.

Rotational force, referred to as torque, affects the angular momentum due to a change in speed of rotation or rotation direction. With the application of external torque in a body, its angular momentum changes. Nonetheless, if torque is not external, the angular momentum remains unaffected, and its rotational motion keeps constant.

This concept is evident in various situations. For example, a figure skater spinning faster by pulling their arms inward demonstrates conservation of angular momentum. The skater changes the distribution of mass in their body without involving any external torque. Similarly, planets orbiting the Sun conserve their angular momentum because no external torque significantly affects their motion.

In essence, angular momentum remains constant only when there is no external torque; it ensures steady rotational motion. Therefore, a moving body will retain its angular momentum if no external torque is applied.

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