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Physics LibreTexts

2: Moments of Inertia

In this chapter we shall consider how to calculate the (second) moment of inertia for different sizes and shapes of body, as well as certain associated theorems. But the question should be asked: "What is the purpose of calculating the squares of the distances of lots of particles from an axis, multiplying these squares by the mass of each, and adding them all together? 

Thumbnail: Moment of Inertia of a thin rod about an axis perpendicular to the length of the rod and passing through its center. Image used with permission (Public Domain; Krishnavedala).