A thin uniform circular disc of mass M and radius R is rotating in a horizontal plane about an axis passing through its centre and perpendicular to its plane with an angular velocity `omega.` another disc of the same dimensions but of mass M/4 is placed gently on the first disc coaxially. The angular velocity of the system now is `2 omega //sqrt5.`

Options

A. `(5)/(4)omega`
B. `(2)/(3)omega`
C. `(4)/(5)omega`
D. `(3)/(2)omega`

Explanation

`(1)/(2)MR^(2)omega-((1)/(2)MR^(2)+(1)/(2)xx(M)/(4)R^(2))omega'`
`omega'=(4omega)/(5)`