HTML5 Physics Demo

Wheel & axle refraction

Two wheels on a rigid axle cross from a fast surface to a slow one. The leading wheel slows first, turning the whole system toward it — exactly as a wavefront bends when entering a denser medium.

Approach angle from normal — 35° (0° = perpendicular, no bend) Speed ratio fast : slow — 1.5 : 1 Simulation speed — 1.00×

Approach angle θ₁ 35°

Measured exit θ₂ —

Snell's prediction —

Current heading 35.0°

The orange dot on each spoke tracks rolling direction. Pause + Step to watch the transition frame by frame. Swap surfaces to see bending in the opposite direction.