How does the radius affect the moment of inertia?

1 Answer
Mar 23, 2018

Moment of inertia is directly proportional to the square of the radius.

Explanation:

The moment of inertia, #I#, of a single mass, #M#, being twirled by a thread of length, #R#, is
#I = M*R^2#

A body that is being rotated will closely resemble that relationship. The formulas for various geometric shapes are derived with integration. For example, for a solid sphere, moment of inertia is
#I = (2/5)*M*R^2#

I hope this helps,
Steve