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The science
Energy and the shape of the track
A cart of mass m on a track of height y(x) gains kinetic energy as it falls: ½ v² + g y = const, so without friction its speed depends only on height, v = √(v0² + 2 g (h0 - h)). The track here is a natural cubic spline through the white control points, so its slope and curvature are continuous (no sudden jolts).
G-force
The rider feels the normal force N = m (g cosθ + v² κ), where κ = y''/(1 + y'²)3/2 is the track curvature (positive in a valley, negative on a crest). In a valley the g-force rises above 1 g; over a crest it drops, and if N would become negative the rider leaves the seat (airtime). Friction acts as -μN and air drag as -c v|v|; the energy they remove is shown in the energy graph.
Honest simplifications: a point cart that stays on the track (no wheel geometry, banking, loops or lateral forces); the track is a function y(x), so it cannot overhang; the cart reaching the last point ends the lap; g-force is the normal component only.
What to try
- Choose One big drop and read the top speed; then raise friction and watch it fall.
- Choose Steep dip, high g and find the valley where the g-force turns red.
- On Camelback, find the crest where the g-force drops below zero (airtime).
- Drag the second hill higher than the first to make the cart stall.