A certain amusement park ride consists of a large rotating cylinder of radius R = 3.15 m. As the cylinder spins, riders inside feel themselves pressed against the wall. If the cylinder rotates fast enough, the frictional force between the riders and the wall can be great enough to hold the riders in place as the floor drops out from under them. A person is completely inside a large, vertical cylinder. The central axis of the cylinder is marked with a dashed, vertical line. The radius of the cylinder is capital R. A curved arrow below the cylinder points to the right to indicate counterclockwise rotation of the cylinder about its central axis if viewed from above. The person inside the cylinder has their back against the right interior wall of the cylinder with their feet above the base of the cylinder. If the cylinder makes f = 0.470 rotations / s , what is the magnitude of the normal force F N between a rider and the wall, expressed in terms of the rider's weight W ?