Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed, holding energy as rotational energy. When energy is extracted, the flywheel's rotational speed declines as a consequence of conservation of energy; adding energy correspondingly results in an increase in the speed of the flywheel.

Most FES systems use electricity to accelerate and decelerate the flywheel, but devices that directly use mechanical energy are under consideration.
Ben works with a flywheel, and has been instructed at various times to change the speeds based on certain conditions. He operates a device that gives or limits the flywheels energy by turning a crank left to give more energy, or right to decrease energy.
Will the flywheel go faster or slower if the crank is turned to the left?