Skydiving simulation with Perl
Computer game programmers apply physical formulas and special tricks to create realistic animations. Simple DirectMedia Layer (SDL), which is available as a Perl wrapper, provides a powerful framework for creating simple 2D worlds with just a couple of lines of code.
After ripping an old VHS cassette of my tandem skydive, posting it on YouTube, and mailing the link to a couple of guys at work, a debate about the physical laws that apply during a parachute jump ensued.
In a simplified model that ignores crosswinds, the jumper starts with a vertical speed of vy = 0 and immediately starts to accelerate because of gravity. Drag, which grows proportionally with the skydiver’s downward speed, counteracts gravity. Depending on the skydiver’s weight and proportions, a balance of forces occurs at around 180 km/ h, and the downward speed becomes constant. At this point, skydivers feel like they are floating in space, and this state continues until the chute opens, which feels like they are being pulled upward with a rope.