Moment Of Inertia Help!! people , i'm a student , and this is a complicated problem i came across ! please noe that i know da simplest of integration and differentiation and the like . it might sound stupid , but can anyone tell why , during the calculation of moment of inertia of a ring the limits during integration are taken as R and 0 , instead of R and -R as in other cases like sphere and rod etc. i noe a bit of calculus just to do about these things only . please help !!! got a hard exam !!