Chapter 12, Problem 13A

What does it mean to Say that angular momentum is conserved?

To determine

To explain: The meaning of conservation of angular momentum.

Explanation of Solution

Introduction:

Angular momentum is the property of any object in circular motion. For an object revolving around a particular axis, the angular momentum is mainly governed by the revolving speed of that object and rotational inertia of that object about that particular axis. The expression for angular momentum $\left(L\right)$ of any object can be written as,

  $L=I\omega$

Where, $I$ is the moment of inertia of an object and $\omega$ is its angular velocity.

Angular momentum of an object is conserved in the absence of an external torque. If there is a change in the shape of revolving object (and hence it’s rotational inertia), there will be a change in its revolution speed if there is no external torque acting on it. Hence the product of rotational inertia and the revolving speed of that object remains constant and hence the angular momentum is conserved.