[SOLVED] Circular motion, static friction 1. The problem statement, all variables and given/known data Hey, this is more of a concept question than a homework question, but here goes: If a ball is spun fast enough to move around the inside of a vertical cylinder at a roughly constant velocity for a few seconds without spiraling down the cylinder, what forces are acting on the ball? 2. Relevant equations 3. The attempt at a solution I think the centripetal acceleration is provided by a normal force from the cylinder on the ball. Static friction must be preventing the ball from "falling" (that is, static friction cancels out the weight of the ball). I'm unsure about the "tangential" forces- I know the ball moves around the cylinder due to static friction, but I am unsure what force causes the ball to slow down... Is it rolling friction? Is there any occurance of kinetic friction in this situation? Thanks for any help.