## Physics: Principles with Applications (7th Edition)

A hoop has twice the moment of inertia of a solid disk of the same mass and radius. The kinetic energy is proportional to the moment of inertia, $KE = \frac{1}{2}I \omega^2$. Spinning at the same angular speed, the wheel with the spokes will have almost twice the kinetic energy of the solid wheel. It only has “almost twice the KE” because the spokes contain some mass, so the spoked wheel isn’t a perfect hoop.