(Solved): Wrecking balls are used to demolish old buildings. A 670 kg steel ball is suspended from a 10-m-lon ...

Wrecking balls are used to demolish old buildings. A 670 kg steel ball is suspended from a 10-m-long cable on a crane. A hook on the crane slowly pulls the ball back, then releases it. The ball's speed at the lowest point in its arc, just before striking the building, is \( 4.5 \mathrm{~m} / \mathrm{s} \). Part A At the lowest point in the ball's arc, the tension in the cable is less than \( m g \) because the ball is moving down. the tension in the cable is equal to \( m g \) because tension and gravity are the only forces and they balance. the tension in the cable is greater than \( m g \) because there has to be a net upward force.