Hello, 1. The problem statement, all variables and given/known data This is not really a homework, but it can be viewed as one. I am trying to design the animation for a roulette ball, but I stumbled over a problem. On a real roulette wheel just over the numbers, there are some small bumps (i don't know the technical name) that make the trajectory of the ball change. Knowing the direction, the speed and the mass of the ball, what will be the new direction of the ball, after the collision with the bump? The ball is moving over a curved trajectory, but, on small portions, it can be considered linear. Also the bumps can be approximated with an ellipse, or even a circle. Any help is appreciated... some links or even a start point for my research. Thanks in advance.