In a fly wheel, most of the mass is concentrated at the rim. Explain why?

Dear student, This is because the flywheel has to have a high moment of inertia. So, the mass has to be located at maximum distance from the center so that we can get more moment of inertia and still use lesser material. Or in other words we can say that, a flywheel having more mass concentration over the periphery will have higher moment of inertia and will be able to store more energy as compared to a flywheel of same mass having more mass concentration near the center . Regards