A flywheel is a mechanical device that stores rotational energy. It is typically made of a heavy wheel that is attached to a rotating shaft. When the wheel is spun, it stores energy in the form of kinetic energy. This energy can then be used to power other devices, such as engines or generators.
Flywheels are often used in applications where there is a need for a reliable and efficient source of energy. They can be used to store energy from renewable sources, such as solar or wind power. They can also be used to provide backup power in the event of a power outage.