I'm working on a simple game, with a ball rolling through some pipes. In Unity 4.3.4, everything was perfect with the default settings - no physics materials used, and the ball would roll very realistically. I upgraded to 4.5, now the ball just 'slides' when it hits an angled edge collider, it is as though the angular momentum is not being calculated correctly. Imaging the ball is falling straight down and hits a 45 degree angle - it does not acquire any angular velocity, it just bounces without rotating at all (in 4.3.4, it would acquire spin when it struck the collider). Then when it hits a horizontal collider, the lack of angular velocity causes it to stick (well not actually stick, just slow down unrealistically). I tried all combinations of material properties (friction and bounce) but this just made things worse. I've just reverted to 4.3.4 and everything is fine again. Works in 4.3.4, broken in 4.5 Should I be doing something different in 4.5, am I missing something new, or is there a bug in the 2D physics?