A round disc of moment of inertia `I_2` about its axis perpendicular to its plane and passing through its centre is placed over another disc of moment of inertia `I_1` rotating with an angular velocity `omega` about the same axis. The final angular velocity of the combination of discs is.

Options

A. `(l_(2)omega)/(I_(1)+I_(2))`
B. `omega`
C. `(I_(1)omega)/(I_(1)+I_(2))`
D. `((I_(1)+I_(2))omega)/(I_(1))`

Answer

C

Explanation

`I_(1)omega=(I_(1)+I_(2))omega_(2)`
`implies omega_(2)=(I_(1)omega)/(I_(1)+I_(2))`