A car is designed to get its energy from a rotating flywheel in the shape of a uniform, solid disk of radius 0.550 m and mass 560 kg. Before a trip, the flywheel is attached to an electric motor, which brings the flywheel's rotational speed up to 5.30 10³ rev/min.

(a)Find the kinetic energy stored in the flywheel (in J).

(b)If the flywheel is to supply energy to the car as a 13.0 hp motor would, find the length of time in hours the car could run before the flywheel would have to be brought back up to speed.