angulaarmoment

Angular momentum is a fundamental concept in physics, representing the rotational equivalent of linear momentum. It is a vector quantity, meaning it has both magnitude and direction, and its value depends on the mass of an object, its velocity, and its distance from a point of rotation. For a single point particle, angular momentum is defined as the cross product of its position vector (from the origin) and its linear momentum. For a rigid body rotating about a fixed axis, angular momentum is the product of its moment of inertia and its angular velocity. The moment of inertia is a measure of how resistant an object is to changes in its rotational motion, analogous to mass in linear motion.

A key principle in physics is the conservation of angular momentum. This principle states that if no external torque acts on a system, its total angular momentum remains constant. This means that as an object's distribution of mass changes, its angular velocity must adjust to keep the total angular momentum the same. A common example is a figure skater pulling their arms in to spin faster. The skater's moment of inertia decreases as their mass is brought closer to the axis of rotation, and to conserve angular momentum, their angular velocity increases. This principle applies to a wide range of phenomena, from the orbits of planets to the behavior of subatomic particles.