Four similar point masses (m each) are symmetrically placed on the circumference of a disc of mass M and radius R. Moment of inertia of the system about an axis passing through centre O and perpendicular to the plane of the disc will be

Options

A. `MR^(2)+4mR^(2)`
B. `MR^(2)+(8)/(5)mR^(2)`
C. `mR^(2)+4MR^(2)`
D. `(MR^(2))/(2)+4mR^(2)`

Answer

D

Explanation

Total moment of inertia of the system
`=(1)/(2)MR^(2)+4mR^(2)=(1)/(2)(M+8m)R^(2)`