A cotton reel rolls without sliding such that the point P of the string has velocity v = 6 m/s. If r = 10 cm and R = 20 cm then the velocity of its centre C is

As cotton reel rolls point of contact of reel with ground will acts as instantaneous axis of rotation.vp = ω(R+r)⇒ω = vpR+r = 20 rad/sVelocity of centre of reelvC = ωR = vpR(R+r) = 6×20(20+10) = 4 m/s