SimuTech Group Blog Comment on How to Extract Moments of Inertia for Point Masses and Simplify Your Model by Kenneth Caamerb

We defined an object's moment of inertia (I) as the sum of its point masses, or (as it is written). The moment of inertia for any object relies on the selected axis since r is the distance from each mass component that makes up the object to the axis of rotation. To illustrate this, let's compute the moment of inertia at two distinct axes for the simple case of two masses at the end of a massless (relatively light mass) rod (see figure). Because the two masses at the end of the barbell can be thought of as point masses, the summation over the masses in this situation is straightforward and only has two terms.