Physics

Say I have a cylinder, ontop of another cylinder. If I move the bottom cylinder to the right, so that its barely touching the top cylinder, how do I make the top cylinder fall down with the right rotation?

...get a physics engine. :)

There are a few physics engines that people have written wrappers for, like newton and ODE.

I didn't use any but people say JV-ODE is great.

I've used/use JV-ODE and certainly rate it... try a demo.

It´s a very simple task with JV-ODE. Lots of useful examples included.