A uniform disc of mass `m` and radius `R` has an additional rim of mass `m` as well as four symmetrically placed masses, each of mass `m//4` tied at positions `R//2` from the centre as shown in Fig. What is the total moment of inertia of the disc about an axis perpendicular to the disc through its centre?

Explanation

`I=I_("disc")+I_("ring")+I_("point masses")`
`=(mR^(2))/2+mR^(2)+[m/4+(R/2)^(2)]=(7mR^(2))/4`