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 what speed is the block going down at that instant?
2 m/s
The Block is moving the rim of the pulley
The pulley is moving at ω = 10 rad/s
The radius of the pulley = 20 cm
Therefore linear velocity on the rim = tangential velocity = rω
= 2 m/s.