So in most of intro physics rolling questions, the masses are assumed to be rigid. So if I roll a sphere on frictional plane, it will move forward and the friction force will help stablize it until pure roll. However, how can there even be a friction force assumed in these problems? The point of contact is one point of dimension 0. How can a friction force be exterted on this point? Also, even if it could be pushed. There is no point paralell to it to push it as all the points in the plane are constantly below it.