Finding the Moment of Inertia from a Point to a Ring to a Disk to a Sphere.

Photo: Rhett Allain

If you want to find the moment of inertia for a rigid object (like a disk or a sphere), you should first ask yourself two questions:

• What is the moment of inertia?
• Why am I doing this?

Here are the answers to those questions. For the moment of inertia, here is my short explanation…