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Two discs A and B are mounted coaxially ...

Two discs `A` and `B` are mounted coaxially on a vertical axle. The discs have moments of inertia `I` and `2I`, respectively, about the common axis. Disc `A` is imparted an initial angular velocity `2w` using the entire potential energy of a spring compressed by a distance `x_(1)`. Disc `B` is imparted an angular velocity `omega` by a spring having the same spring constant and compressed by a distance `x_(2)`. Both the discs rotate in the clockwise direction.
When disc `B` is brought in contact with disc `A`, they acquire a common angular velocity in time `t`. The average frictional torque on one disc by the other during this period is

A

2

B

`1/2`

C

`sqrt(2)`

D

`1//sqrt(2)`

Text Solution

Verified by Experts

The correct Answer is:
C
`1/2I(2omega^(2)) = 1/2kx_(1)^(2)` and `1/22I(omega)^(2) = 1/2 kx_(2)^(2)`
Dividing them, we get: `X_(1)/X_(2) = sqrt(2)`.
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