Some special vehicles have spinning disks (flywheels) to store energy while they roll downhill. They use that stored energy to lift themselves uphill later on. Their flywheels have relatively small rotational masses but spin at enormous angular speeds. How would a flywheel’s kinetic energy change if its rotational mass were 7 times larger but its angular speed were 7 times smaller?

Question

KE2/KE1 =

Answer 1

Ke = (1/2) I w^2

KEmodified = (1/2)(7I)(w^2/49) = original Ke/7