1. The problem statement, all variables and given/known data In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-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 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. What is the minimum rotational frequency, in rpm, for which the ride is safe? 2. Relevant equations I'm not even certain which equations would be relevant here. Starting with a free body diagram, I can see that the weight force would point down, and the opposing force would have to be static friction so that would point up, and the centripetal acceleration would be due to the normal force from the walls. So N = mv^2/r (But I don't have a given mass; should I be able to find mass from the given coefficients of friction since friction counters weight in this situation?) Force of static friction = u * N (But I don't know how to find N-- is it still opposing mg if it is in the horizontal direction? If so, I still don't know how to find m…) v= 2π r/T Also, v = wr, and then I can convert to rpm… Is this even relevant here, given that I don't have a time period to work with anyway? Are my thoughts so far on the right track or am I way out in left field? Any nudge in the right direction would be greatly appreciated.