One quarter sector is cut from a uniform circular disc of radius R. This sector has mass M. It is made to rotate about a line perpendicular to its plane and passing through the center of the original disc. Its moment of inertia about the axis of rotation is

Question

G1 Physics · Accepted Answer

For a circular sector of angle π/2 and mass M, the moment of inertia about the original disc centre is I=∫r²dm. Because the radial mass distribution is the same as for a full disc, I=½MR². Hence option A.