A disc of mass M and radius R is suspended in a vertical plane by a horizontal axis passing through its centre. After sticking an object of same mass M at its rim the mass is raised to the position of maximum height. Now this unstable system is released. when the object passes the position right below the centre the angular velocity of the system would be

Options

A. `sqrt((8g)/(3R))`
B. `sqrt((2g)/(3R))`
C. `sqrt((3g)/(2R))`
D. `sqrt((3g)/(8R))`

Answer

A

Explanation

Using energy conservation
`2MgR=1/2((MR^(2))/2+MR^(2)) omega^(2) , omega=sqrt((8g)/(3R))`