1. The problem statement, all variables and given/known data A 10g steel marble is spun so that it rolls at 150rpm around the inside of a vertically oriented steel tube. The tube is 12 cm in diameter. Assume that the rolling friction is small enough for the marble to maintain 150 rpm for several seconds. During this time, will the marble spin in a horizontal circle, at constant height, or will it spiral down the inside of the tube. Known 150rpm 12cm diameter coefficient of Static friction for steel on steel (dry)=.80 2. Relevant equations A=V^2/r Fsmax=(mew)s x n 3. The attempt at a solution I solved for the velocity which came out to be .3pi m/s for the ball and then got stuck from there. I solved for the centripetal acceleration but dont know if that would apply in this situation. I know that I need to find the normal force so I can figure out the static max, and in order for the ball to remain horizontal it must be under the static max right? Any insight that would aim me in the right direction would be very much appreciated.