Fig. 3. — Another Form of Expression for the Energy of a Rotating Body May be obtained by Determining Its Moment of Inertia. Here the Mass M Is Subdivided Into Minute Parts m1, m2, m3, … etc. The Sum of the Products of These Masses and the Squares of Their Distances is the Moment of Inertia, Which with the Angular Speed, Gives the Kinetic Energy E.