HomeSciencePhysicsWhat is Angular Momentum?
Science·1 min·Updated Mar 11, 2026

What is Angular Momentum?

Angular Momentum

Quick Answer

It is a measure of the rotational motion of an object, combining its mass, shape, and speed of rotation. Angular momentum helps explain how objects move when they spin or rotate around an axis.

Overview

Angular momentum is a fundamental concept in physics that describes the quantity of rotation an object has. It depends on three main factors: the object's mass, the distance from the rotation axis, and its velocity. When an object spins, it has angular momentum that can be transferred or conserved, which is crucial in understanding motion in different systems. For example, consider a figure skater performing a spin. When they pull their arms in close to their body, they reduce their distance from the axis of rotation, which causes them to spin faster. This illustrates the conservation of angular momentum, where the total amount remains constant even as the skater changes their position and speed. Understanding angular momentum is important in various fields, from engineering to astronomy. It helps explain phenomena such as the orbits of planets and the behavior of spinning objects. By studying angular momentum, scientists can predict how objects will move and interact in a rotational context.


Frequently Asked Questions

Angular momentum is typically measured in kilogram meters squared per second (kg·m²/s). This unit reflects the mass of the object, the distance from the axis of rotation, and the speed of rotation.
While linear momentum deals with straight-line motion, angular momentum focuses on rotational motion. Both concepts are related through the object's mass and velocity, but angular momentum incorporates the distance from the axis of rotation.
Yes, angular momentum can change if an external torque is applied to an object. However, in a closed system with no external forces, the total angular momentum remains constant, demonstrating the principle of conservation.