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## Homework Statement

A slab has width a, length a, and thickness a/4. What is the moment of inertia about its symmetry axis?

Use the one parallel to the large face of the slab.

## Homework Equations

## The Attempt at a Solution

The answer is supposedly (ma

^{2})/12 + m(a/4)

^{2}/12.

I can't see why so I tried to verify it using integration, but that's not working either. Basically I tried to find the moment of inertia of a thin plate, dimensions a x a. I found that to be ma

^{2}/12 like I should.

Then I wanted to basically take a stack of thin plates to make one thick plate of thickness a/4. But I can't figure out what the calculus for that would look like. Help?