physics - help

Question

 Michelle swings a 0.009-kg rubber stopper around her head. The rubber stopper is tied to a string that Michelle holds at 0.72 m with a force of 21. N. If she lets go of the string, what is the tangent velocity at which the rubber stopper would fly off?

Answer 1

It would fly off at the velocity it had while in circular motion.

 

mv²/r = F

 

v = √(rF/m) = √(0.72*21/0.009) m/s ≅ 41.0 m/s