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.
The Attempt at a Solution
The answer is supposedly (ma2)/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 ma2/12 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?