One way to store energy is in the rotational motion of a flywheel, and some have proposed using such technology to power automobiles. One unit is based on a 7.0- kg
flywheel in the shape of a hoop of radius 0.10 m
that spins as fast as 50000 rpm
.
How much kinetic energy is stored by the flywheel when it is rotating at its maximum rate?
Express your answer to two significant figures and include appropriate units.