Q. 11
a horizontal disc rotates freely with angular velocity '' about a vertical axis through its centre. A ring, having the same mass and as the disc, is gently placed on the disc. The common angular velocity with which the two rotate, will be
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As ring is gently placed
So torque will be 0
therefore angular momentum is conserved
let w be common angular velocity
initial angular momentum = 1/2 m r^2 W = ( 1/2 mr^2 + mr^2) w
= 1/2W = 3/2 w
w = W/3
So torque will be 0
therefore angular momentum is conserved
let w be common angular velocity
initial angular momentum = 1/2 m r^2 W = ( 1/2 mr^2 + mr^2) w
= 1/2W = 3/2 w
w = W/3
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