Fun with Conservation of Energy. When you release the weight, it has all the energy it’s going to have. Specifically, it’s loaded up with a form of energy called potential energy, or stored energy. As soon as you let go, gravity pulls the weight down and the potential energy starts converting to another type called kinetic energy, the energy of motion. At the bottom of the swing, all potential energy is fully transformed into kinetic energy. As it climbs up the other side, the kinetic energy starts changing back into potential energy. This repeats over and over: potential turns to kinetic, kinetic turns to potential. But the transformation between potential and kinetic energy isn’t perfect. Friction from the air and the rope steals some of the energy during every swing. That energy goes into heating up—very slightly—the air, the rope, and the support beam (E =mc2). When the weight is coming back to your face, it has less energy than it started with and can’t climb as high. Your nose is perfectly safe! NeilDeGrasseTyson Physics Energy boop Disclaimer: If you are going to try this, do not add any additional momentum to the rope when releasing it or you are going to have a bad time.