Question

A mass m = 0.225 kg on a frictionless table is attached to a hanging mass M = 0.330 kg by a cord through a hole in the table (see the figure). Find the speed with which m must move in order for M to stay at rest if r = 27 cm.

Answer 1

Hmmm. I assume M is rotating.

Mv^2/r=mg

solve for v.