A flywheel is a solid disk that rotates about an axis that is perpendicular to the disk at its center. Rotating flywheels provide a means for storing energy in the form of rotational kinetic energy and are being considered as a possible alternative to batteries in electric cars. The gasoline burned in a 142-mile trip in a typical midsize car produces about 4.28 x 109 J of energy. How fast would a 31.1-kg flywheel with a radius of 0.487 m have to rotate to store this much energy? Give your answer in rev/min.