1. The problem statement, all variables and given/known data We place a rubber on the edge of a rotating disk. What forces act on the rubber? At what angular velocity, why and in what direction will the rubber fly off the disk? 2. Relevant equations http://images.tutorvista.com/cms/formulaimages/83/angular-speed-formula111.PNG [Broken] 3. The attempt at a solution I guess there is a centrifugal force that acts against the frictional force between the disk and the rubber. As long as they balance each other out, the rubber seems to be at rest. When the angular velocity reaches a given speed, the centrifugal force will exceed the frictional force and the rubber will leave the disk. I suppose the rubber leaves the disk on a tangential path, but I cannot explain the reasons behind it and have no idea about the exact angular velocity at which the object flies off the disk. Thank you in advance.