please show me how to solve symbolically while solving the problem

1. 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 292-mile trip in a typical midsize car produces about 2.12 * 10 ^ 9 of energy. How fast would a 6.53-kg flywheel with a radius of 0.485 m have to rotate to store this much energy? Give your answer in rev/min. 2. A solid sphere is rolling on a surfaceWhat fraction of its total kinetic energy is in the form of rotational kinetic energy about the center of mass? 3. A marble and a cube are placed at the top of a ramp. Starting from rest at the same height, the marble rolls without slipping and the cube slides (no kinetic friction) down the ramp. Determine the ratio of the center-of-mass speed of the cube to the center-of-mass speed of the marble at the bottom of the ramp