1. The problem statement, all variables and given/known data A ball is moving along a frictionless surface, after a force is applied. Does the surface need friction for the ball to actually rotate? If so why? Is the ball actually moving horizontally or is it just rotating? 2. Relevant equations The force applied is that big arrow. http://img709.imageshack.us/img709/2935/rollign.png [Broken] bottom line is the surface. 3. The attempt at a solution I'm thinking that it doesn't need a a frictional force because the tangential force can already provide the rotation. What I'm thinking is that the ball is not moving unless there is a frictional force, but I'm not sure why.