I can't determine LL's policy about borrowing from wikipedia. I don't think they want to deal with the GFDL, so what I am doing here is putting in MY edits from wikipedia. Since the text came from ME, there is no GFDL attached to this contribution.
My wikipedia edit histories: http://en.wikipedia.org/w/index.php?title=Physics_engine&diff=119186741&oldid=115503853
Also adding some material from my in-world PaddleWhack physics toy: http://slurl.com/secondlife/Chilbo/188/53/95
Scalar Tardis 01:39, 23 February 2008 (PST)