Halliday, Resnick & Walker — Potential Energy and Conservation of Energy: Problem 70_GO

In Fig. 8.21, the string is \( L = 120 \text{ cm} \) long, has a ball attached to one end, and is fixed at its other end. A fixed peg is at point P. Released from rest, the ball swings down until the string catches on the peg; then the ball swings up, around the peg. If the ball is to swing completely around the peg, what value must distance \( d \) exceed? (Hint: The ball must still be moving at the top of its swing. Do you see why?)