Hello Unity Community! Since Unity 5.1 I found out that there is a bug or unexpected behaviour of physics or implementation of AddForce / AddTorque on collisions of two colliders. I have the following scenario: when user touches the screen the player accelerates (addForce) until the player reaches a given MaxSpeedBound, that is checked in the FixedUpdate, where the addForce is applied. When the player touches another collider(not trigger) he is slowed down, just the way it should be, with correctly computed physics properties from Unity 4.3 to 5.0. But with 5.1 what happens on collision now is: The colliding object just flies off as fired from a shotgun and the speed of the player becomes many times of MaxSpeedBound, flying also like crazy. It seems that AddForce adds potential energy, which cannot be detected when comparing if the current speed < MaxSpeedBound, since its "potential" speed, and potential force cannot be read out so far. So ignoring the speed check the addForce adds within some milliseconds on collision with other colliders many times potential energy and the so blown up potential energy becomes kinetic energy and both object fly away at the "speed of light." As I wrote, in Unity 4.3 to Unity 5.0 nothing like this was happening, now I am desperate :-/ Is this a bug or a feature of Unity 5.1?