physics
posted by Sandhya .
A bicycle with wheels of 70.0 cm diameter is going at a speed of 12.0 m/s.How fast is a point on the rim at the top of one of the wheels moving relative to the ground?

The angular velocity of the wheel is
w = V/R = 12.0/0.700 = 17.14 rad/s
Because the contact point of the wheel with the road is an "instant center" of rotation, a point at the top of the wheel moves at a velocity 2 w = 2 R * (V/R) = 2 V = 24 m/s. 
Thanks for your quick response