A popular amusement park ride looks like a huge cylinder of radius 2.3 m, where people stand up along the vertical walls on top of a floor which can drop away. The cylinder begins to rotate faster and faster, and when it reaches its highest speed the floor drops away. Clearly static friction is holding the people in place against the wall. Assuming that the coefficient of static friction is 0.5, what are the minimum rotations per second the cylinder must make so that the people are safe?