Ok so I'm writing a 3D game that uses impulse to determine how things behave when they collide. In this game I have two cubes. Now the shape of each cube is defined by 9 spheres, sort of like this: http://mark.reid.name/images/figures/high-dim-3d.png Though in my game the middle sphere is larger. I am using the equations found here: http://www.euclideanspace.com/physics/dynamics/collision/threed/index.htm So far everything works as it should except for one small detail. If I line the cubes up and place them as close as possible to each other, sort of like this: http://static-p3.fotolia.com/jpg/00/11/43/92/400_F_11439295_zmVtzYajNbkN71oe6l6lThBQHhRWxkQm.jpg (and btw these aren't from my game their just random pictures from the internet I thought might be helpful). Anyways if I position the cubes as shown in that picture I am able to rotate them through each other, which is obviously not what would happen in real life. Basically If the cubes have only linear velocity or have linear velocity and angular velocity everything works. But if the cubes only have angular velocity and are next to each other like in the picture they will rotate through each other. Keep in mind this isn't due to the fact that the collision of the cubes is represented with spheres. I am able to see the spheres that compose the cubes and can clearly see them going through each other (I also tried this with rectangles where it became very obvious something was wrong). I would think in this type of situation that one of two things should happen: 1) In the case they are perfectly lined up and the angular velocity is small then nothing should happen . 2) In the case that they are not perfectly lined up but are still close or when the angular velocity of one of them is really large they should turn each other like gears. I have checked my code again and again and have found nothing wrong. I believe that the equation I found at the euclidean space site does not account for this type of motion. So does anyone know how to account for this type of motion and how I could incorporate it into my current equation?