## Essential University Physics: Volume 1 (4th Edition)

We know that the mass will be located at the average of the two radii. Thus, we find: $I_{ring} = \frac{MR_1^2 + MR_2^2}{2}$ $I_{ring} = \frac{M(R_1^2 + R_2^2)}{2}$ $I_{ring} = \frac{1}{2}M(R_1^2 + R_2^2)$