The mass of a disk of radius R and thickness t is not uniformly distributed; it has density, i.e., mass per unit volume, (r ) = 0/[1 + r 2/R2], where 0 is the density at the center and r is the distance from the axis of symmetry. Find (a) the total mass M of the disk, and (b) the moment of inertia around an axis perpendicular to the disk and passing through its center. (c) Express the moment of inertia in terms of M and R, and compare the result with the rotational inertia of a disk with the same M and R, but with uniform mass density. Comment on the difference