How do I calculate the centrifugal force of a 20g ball on a 1,5m piece of string swinging at 30km/h? Please!?

Question

I have been told that the formula is mv2 over r........but I don't understand how to calculate the answer at all. Do I multiply the mass (20g) by the velocity (30km/h) ...or what?? Please can someone explain this to me?

Answer 1

velocity squared, times the mass, divided by the radius, right?

Make sure your units are correct (m vs km, etc).