Flywheel

http://vantagehsi.com/tips-for-better-communication-with-patients-who-suffer-from-alzheimers-disease/ A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a revolution rate of a few thousand RPM. Some modern flywheels are made of carbon fiber materials and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM.