A christmas bulb of mass W is swung in a vertical circle on a cord length Y. What minimum speed v needed at the top of the circle to keep the cord taut?

Answer 1

v^2/Y = g
v = sqrt(Y*g)

W does not matter.

Answer 2

A 55kg Man is on a merry go round and is 15m from the center. It takes 4.5 seconds for 1 complete trip. What is ac and fc?