Release a ring, a disc and a sphere together down a ramp and see who reaches the bottom first — and why. They all feel the same gravity, but each body must spin up its own moment of inertia, so the one that hides the least mass far from its axis wins.
RingDiscSolid sphereShellRolling without slipping
Setup
Incline angle θ20 °
Ramp length L4.0 m
Racers
Solid sphere wins
Finish order
3.36
winner a (m/s²)
5.18
v at bottom (m/s)
71
% KE translation
1.19
winner time (s)
a = g·sinθ / (1 + I/mR²)ring 1 · disc ½ · sphere ⅖ · shell ⅔independent of m and R
Playback
Try this: mass and radius don't matter — only the shape. The solid sphere hoards the least mass at its rim, so it always beats the disc, the shell and (dead last) the ring, no matter how heavy or big you imagine them.