🎳 Moment of Inertia (Rolling Race)

📖 The Physics

Just as mass measures how hard it is to push something into motion, the moment of inertia measures how hard it is to get something spinning. The twist is that it depends on where the mass sits, not just how much there is.

Mass far from the axis (a ring) resists rotation much more than the same mass packed near the axis (a solid sphere) — even for identical total mass and radius.

Same mass, same radius, same ramp — yet the sphere always wins, the disc is second and the ring is last, because a smaller moment of inertia means less energy tied up in spinning and more speed. The order never depends on the mass or radius.