## Essential University Physics: Volume 1 (3rd Edition)

$\frac{5}{8}MR^2$
We add the inertias of the inner and outer rings using the equation for the moment of inertia of a ring: $I =(\frac{1}{2}M)(\frac{1}{2}R)^2+(\frac{M}{2})R^2=\frac{5}{8}MR^2$