I have said this in the past... I shall probably repeat it again in the
future...
If you're into programming games on a mac grab a copy of tricks of the 'mac
Game programming Gurus' - you should find a link to it and all the relevant
details in the euroFB bookshop (go to <http://euro.futurebasic.com/> and
seek out the book store.

You will find all sorts of physics, vectors, matrices and all to get your
games moving smoothly and funly.

All the best
:-j