The discussion centers on whether the frictional force acting on a rolling sphere on a rough surface can be zero. Participants debate the conditions under which friction may not be necessary, emphasizing that if the sphere is rolling without slipping and no net external forces or torques are acting, then friction can indeed be zero. However, if external forces are present, such as when rolling down an incline, friction becomes essential to oppose these forces. The conversation also touches on the implications of changing the surface to a smooth one, which would result in slipping rather than rolling. Ultimately, the consensus is that while friction can be zero under specific conditions, it is crucial for maintaining rolling motion in the presence of external forces.
