Flywheel | Energy Storage, Kinetic Energy & Momentum | Britannica
flywheel, heavy wheel attached to a rotating shaft so as to smooth out delivery of power from a motor to a machine. The inertia of the flywheel opposes and moderates fluctuations in the speed of the engine and stores the excess energy for intermittent use. To oppose speed fluctuations effectively, a flywheel is given a high rotational inertia ...