Suppose you swing a ball of mass m in a vertical circle on a string of length L. As you probably know from experience, there is a minimum angular velocity ω_min you must maintain if you want the ball to complete the full circle without the string going slack at the top.
a. Find an expression for ω_min.
b. Evaluate ω_min in rpm for a 65 g ball tied to a 1.0-m-long string.