Angular Momentum

Angular momentum (L) is a measure of the amount of rotation an object has, taking into account its mass distribution and rotation speed. It is calculated by multiplying the moment of inertia (I) of the object by its angular velocity (ω). The moment of inertia represents the resistance of an object to changes in its rotational motion and depends on the distribution of the object's mass relative to the axis of rotation. Angular velocity is the rate at which an object rotates or revolves, measured in radians per second (rad/s). In this formula, angular momentum is measured in kilogram square meters per second (kg·m²/s).

This concept is crucial in physics, especially when dealing with rotating systems like wheels, planets, or atoms. For rigid bodies, the moment of inertia is constant and can be calculated based on the shape and mass distribution of the body. Angular momentum is conserved in a closed system without external torques, making it a central principle in classical mechanics and astrophysics. For example, it explains why an ice skater spins faster when pulling their arms in—they are reducing their moment of inertia, and to conserve angular momentum, their spin rate (angular velocity) increases accordingly.