Ball physics engine

hi!

I’m looking for a good physics engine similar to this:

http://spamtheweb.com/ul/upload/130509/70214_tank.php

That was made using flade, but I cannot use flade, because the graphics are AS-based, and it will be impossible for me to edit the code in the future.

I’m using AS2. And I’d prefer for the ball to roll on sloped hills, but if not, that’s fine too, I can add that in myself.

Thanks in advance to everyone who tries to help