Two discs of moments of inertia `I_(1) and I_(2)` about their respective axes (normal to the disc and passing through the centre), and rotating with angular speed `omega_(1) and omega_(2)` are brought into contact face to face with their axes of rotation coincident . What is the angular speed of the two-disc system ?

Options

A. `(I_(1)+I_(2))/(I_(1)omega_(1)+I_(2)omega_(2))`
B. `(I_(1)+I_(2))/(I_(1)omega_(1)-I_(2)omega_(2))`
C. `(I_(1)omega_(1)+I_(2)omega_(2))/(I_(1)+I_(2))`
D. `(I_(1)-I_(2))/(I_(1)omega_(1)+I_(2)omega_(2))`

Answer

C

Explanation

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