A van is designed to get its energy from a rotating flywheel with a radius of 1.6 meter and a mass of 490 kilogram. Before a trip, the disk shaped flywheel is attached to an electric motor, which brings the flywheel's rotational speed up to 1002 rev/min.
a) Compute the kinetic energy stored in the flywheel.
b) If the flywheel is to supply as much energy to the van a7457 W motor would, compute the length of time the van can run before the flywheel has to be rough back up to speed again. (s)