how much centripetal force is needed to make a body of mass 0.5 kg to move in a circle of radius 50 cm with a speed 3ms-1

9 N

Explanation:

The centripetal force F is F = mrω^2 = (mv^2) / r where m is mass, r is radius of the curve, ω is angular velocity and v is tangential velocity.

In this case, m = 0.5kg, r = 0.5m, v = 3m/s

So F = [0.5kg (3m/s) ^2]/0.5m = 9kg-m/s^2 which is 9N

F = (mv^2) / r

= (0.5 * 3^2) / 50*10^-2

= 9N