A heavy ball swings at the end of a chain connected to a hook in the ceiling. Suppose I pull the ball away from its equilibrium position, hold it against my nose (with the chain taut), and then release the ball from rest. The ball swings away and then back toward my face. As long as I don't move, and the ball is left alone, I can be confident that the ball will not smash my nose

Question

Quizplus · Accepted Answer

Due to the conservation of mechanical energy in a system where only conservative forces are acting, the ball cannot swing back to a position higher than its initial release point if no external work is done on the system.

A Heavy Ball Swings at the End of a Chain