object physics

i''m trying to build something like a physics engine. since i myself have never really been too keen on physics concerning physical bodies, i don''t know much about them. reading thick books and getting myself up to speed with everything doesn''t seem very likely either because of my studies->lack of time, so i''m trying to find resources on the web to help me out. here''s an abstraction of what i''m trying to do: make a body fall through an atmosphere of somekind and simulate its behaviour when it reaches the ground. i''ve successfully done this with a perfect cube in a perfect environment (no outside forces other than gravity and air resistance) with the cube being initially completely lateral. now, what if i rotated the cube some x degrees around any of its axis. i could figure out the effect of air resitance and other forces during falltime by myself, but i''m not sure as to how to approach the behaviour of the cube when it crashes into something. quick browsing the net led me no place useful - i''d be extremely grateful if someone could tell me a webpage or two to refer to. i''m sure there are dedicated physics pages out there that deal with similar problems! crispy