Hey guys! I'm doing my B.S thesis (Mech. Eng.) and I've come across the problem of a rolling disk with friction. Imagine a disk in real world rolling on a flat surface with no external force or torque applied to it except for the interaction of the surface (Normal, friction, etc.). Now, since this is a real world problem, the disk will eventually come to a stop. However, if you write the equilibrium equations for such a disk using the single point friction model, you will come to a paradox: The friction force (let's say it's acting on the contact point in the opposite direction of moving) gives the disk's center of mass a negative linear acceleration, while the moment of the friction force about the center of mass tends to give the disk a positive angular acceleration! (Don't forget that the disk is in pure rolling, so: linear acc. = R * angular acc.) This is why I need a friction model that doesn't have this bug! I think it should be based on a contact patch instead of a contact point, but I can't go further than that by myself. Can anyone help? Thanks!