Earlier quoted context omitted.
Since we are sharing: I've spent the last couple of years, on and off, building a physics engine from scratch. Pretty hard considering I'm not a mechanical engineer. Lots of fun though.
Excellent! You should do a "Show HN," when you are done. What language are you using? What is your destination platform? UPDATE: I just looked at your HN handle. Questions answered. Good show!
Java
>>What is your destination platform?
Mac, Windows, iPhone, Android