1. The problem statement, all variables and given/known data In an old-fashioned amusement park ride, passengers stand inside a 5.5m-diameter hollow steel cylinder with their backs against the wall. The cylinder begins to rotate about a vertical axis. Then the floor on which the passengers are standing suddenly drops away! If all goes well, the passengers will "stick" to the wall and not slide. Clothing has a static coefficient of friction against steel in the range 0.63 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. A sign next to the entrance says "No children under 30 kg allowed." What is the minimum angular speed, in rpm, for which the ride is safe? 2. Relevant equations Critical velocity=SQRT(rg) F=ma 3. The attempt at a solution I know how to solve these kinds of problems in the absence of friction, but I don't understand what I need to do with these coefficients. Friction points tangentially to the circular motion in the free body diagram, but how does that influence the (Fnet)y?