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Two horizontal discs of different radii ...

Two horizontal discs of different radii are free to rotate about their central vertical axes: One is given some angular velocity, the other is stationary. Their rims arc now brought in contact. There is friction between the rims. Then

A

The force of friction between the rims will disappear when the discs rotate with equal angular speeds.

B

The force of friction between the rims will disappear when they have equal linear velocities

C

The angular momentum of the system will be conserved.

D

The rotational kinetic energy of the system will not be conserved

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The correct Answer is:
b, d
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