# High Jump

> A browser high jump run on World Athletics Technical Rules TR26 and TR27, with an
> anthropometric segment-mass jumper whose centre of mass is computed rather than assumed.

https://high-jump.skillsafe.ai/

## What it is
An independent, unofficial simulation of the athletics high jump. Not affiliated with
World Athletics. Pure client side: no account, no server call, no model, no credits.

## The question it answers
The Fosbury flop is widely said to work because the jumper's centre of mass passes UNDER
the bar. This app derives the answer from published segment masses instead of assuming it.

- The engine's optimised flop clears a bar 4.6 cm ABOVE the peak of its own centre of
  mass. So it is geometrically possible.
- None of the eleven finalists World Athletics measured at the 2018 World Indoor
  Championships did it. All eleven carried the centre of mass ABOVE the bar, +2 cm to
  +12 cm, mean +7.0 cm.
- At the bar plane the modelled flop's centre of mass sits 77 mm OUTSIDE the body, in the
  hollow under the arch. The dive straddle keeps it 33 mm inside the body.
- Clearance efficiency (bar minus centre-of-mass peak), same arc for all five:
  Fosbury flop +4.6 cm, Eastern cut-off -5.8 cm, dive straddle -6.6 cm, scissors -46.8 cm,
  legs-up (1797) -65.0 cm. Dapena (2002) documents the flop-over-straddle gap as 5-7 cm;
  this model makes it 11.2 cm, so the ordering reproduces and the magnitude does not.

## Sources
- World Athletics, Book C - C2.1 Technical Rules (TR25, TR26, TR27), official PDF.
- de Leva, P. (1996), J Biomech 29(9):1223-1230, segment inertia parameters.
- Dapena, J. (2002), ISBS, "The evolution of high jumping technique".
- World Athletics Biomechanical Report, 2018 World Indoor Championships, High Jump Men.
- Wikipedia: High jump, Fosbury flop, Straddle technique, Scissors jump.

## Pages
- / — the game, the Lab panel with every measurement, the Rules panel, and About.
- /CREDITS.txt — sources, the provenance tally, and what is reconstructed.
- /LICENSE.txt — MIT.

## Provenance
77 declared constants and modelling choices: 51 documented, 8 derived, 5 measured,
2 calibrated, 11 reconstructed.