Question

Is the moment of inertia of a hula hoop just \(r^2m\), where \(m\) is the mass of each particle element and \(r\) is the radius of the hoop?

Answer 1

This is the moment of inertia about an axis through the center of mass, perpendicular to the plane containing all elements of the hoop. You aren't expressing it as an integral, therefore m is the total mass of the hula hoop.

Refer here: http://en.wikipedia.org/wiki/List_of_moments_of_inertia Fifth one down.

Answer 2

Dumb moment, ignore me. I apparently don't know what moment of inertia is.