1. The problem statement, all variables and given/known data A billiard ball (of mass m and radius a) is struck by a cue and moves off with initial speed u, sliding (without rotation) along the table top. After what time will the ball roll rather than skid, if the frictional force between the ball and the table has magnitude qmg. (Recall that the moment of inertia of the ball about a diameter is 2/5 ma^2) 2. Relevant equations 3. The attempt at a solution I see at the point when the ball begins to roll the ball will have an acceleration corresponding to a force that is less than the frictional force between the ball and table. But im unclear on how to proceed on finding the time at which this occurs and where the moment of inertia comes into this. Any guidance much appreciated.