1. The problem statement, all variables and given/known data Determine the moment of inertia of a think disk of mass M, with inner radius A and outer radius B, when rotating about an axis perpendicular to the plane of the disk and through its center. 2. Relevant equations The equation of moment of inertia for a disk is I = (m*r^2)/2 my question is that because there are two radii, how does that affect r in the equation? 3. The attempt at a solution I = (m*r^2)/2 then substitute I = (M*r^2)/2 but is r=(B-A)^2 or is r=(B^2-A^2)?