There is a lot about that topic but nowhere an answer. I`m trying to do pretty easy task - mini golf. Have flat ground, have walls, I move ball with addforce function. But when it comes to hit walls, it bounces totally randomly, sometimes even it get back when it hit wall at 45 angle! I read that some people write their own bounce function, but it is a little bit insane when phisycs engine just should do something as simple as wall bounce. I tried very much different configuration, with angular velocity, without, with bouncines, and without, different friction, on ball and on wall, all configuration with wall physics and without. It seems like Unity physics in contatct with walls have their own life and idea about physics Any help, or idea? It... really should be a very simple matter.