Question

A massless rigid rod of length L = 30.2 cm has a ball of mass m = 0.134 kg attached to one end. The other end is pivoted so that the ball moves in a vertical circle. The ball is launched from the horizontal position A with an initial downward speed v₀. It just reaches point D and stops. Calculate v₀.

Answer 1

by applying energy conservation:

$mv_0^2/2=mgL$

$v_0=\sqrt{2gL}=\sqrt{2\cdot 9.8\cdot 0.302}=5.92$ m/s