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A block hangs from a string wrapped on a...

A block hangs from a string wrapped on a disc of radius 20 cm free to rotate about its axis which is fixed in a horizontal position. If the angular speed of the disc is 10 rad/s at some instant, with whtat speed is the block going down at that instant?

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The correct Answer is:
B
The block is moving on the rim of the pulley. The pulley is moving at `omega=10rad/s`
Therefore the radius of the pulley
`=20 cm`

Therefore linear velocity on the rim
=tangential velocity `=romega`
`=10xx20=200cm/s`
`=2m/s`
Therefore velocity of the block
`=2m/s`
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