Question

A rod of length L is composed half of wood mass Mw and half of brass mass Mb find the moment of inertia of the rod about the axis perpendicular to the wood end

Answer 1

  

Moment of inertia M1​=mw​×3(L/2)2​
=mw​12L2​
Moment of inertia M2​=mb​×3(L/2)2​
=mb​×12L2​
Moment of inertia M=M1​+M2​
=mw​12L2​+mb​×12L2​
=(mw​=mb​)12L2​