Description: The coupled pendulum can be created with either string or a spring connecting the two pendulums. With each swing energy is transferred from one pendulum to the other. If the pendulums both have the same length one pendulum comes to a complete stop before alternating motion. This phenomenon can be used to show balanced and unbalanced forces, how motion can be used to predict future motion, and the conservation of energy.
Web Resource: L.R. Ingersoll Physics Museum