Answer:
5.42 m/s
Step-by-step explanation:
At minimum speed, the tension in the bar will be 0 when the ball is at the top of the arc, so the only force is gravity pulling down.
Sum of forces towards the center of the circle:
∑F = ma
mg = m v²/r
v = √(gr)
v = √(9.8 m/s² × 3.00 m)
v = 5.42 m/s