Two wheels A and B are mounted on the same axle. Moment of inertia of A is 6 kg `m^(2)` and is rotated at 600 rpm, when B is at rest. What will be moment of inertia of B, if their combined speed is 400 rpm?

Options

A. `8kg-m^(2)`
B. `4kg-m^(2)`
C. `3kg-m^(2)`
D. `5kg-m^(2)`

Answer

C

Explanation

Applying the principle of conservation of angular momentum, `(l_(1)+l_(2))omega=l_(1)omega_(1)+l_(1)omega_(2)`
`(6+l_(2))(400)/(60)xx2pi=6xx(600)/(60)xx2pi+l_(2)xx0`
`"which gives, "l_(2)=3"kg-m"^(2)`