Energy conversions in a swing
Playground swings offer an excellent example of the conversion between potential and kinetic energy. Hold a swing next to your chin and let go. Try to keep you head still when the swing comes back!
The second photo shows a frame by frame analysis of the motion, obtained by using the Tracker app
Preschool children figure out how to keep a playground swing moving by shifting their body mass, without the need to refer to the concepts of work, energy, or angular momentum.
The figure below shows swinging in a long swing in a park. The shift from squatting to standing up in the lowest point requires work from the muscles in the body. This leads to increased mechanical energy, both potential energy and kinetic kinetic energy. This builds on conservation of angular momentum is the lowest point. (See a symbolic graph of the motion with increasing amplitude.)
You may also search for a video showing the motion of the "Botafumeiro" - the Incense burner in Santiago de Compostela, which makes use of the conservation of angular momentum on a larger scale.