physics
posted by R .
A ball of mass 0.750 kg is attached to the end of a 1.20m long cord that can withstand a maximum tension of 50.0 N. If swung in a vertical circle, what is the maximum velocity the ball can achieve before the string breaks?

Since the circle is vertical, maximum tension is experienced when the ball is at the bottom of the loop. Tension must support both weight and centripetal force.
Require that
M*V^2/R + M*g = (maximum tension) Tmax
= 50.0 N
Then solve for V.
M*V^2/R = 50  7.35 = 42.65 N
V = sqrt(42.65*1.2/0.75)= 8.26 m/s