The wall of death in an amusement park is comprised of a vertical cylinder that can spin around the vertical axis. Riders stand against teh wall of teh spinning cylinder and the floor falls away leaving teh riders held up by friction. The radius of the cylinder is 3.9 m and the coefficent of static friction between the wall and the rider is .33. Find the tangential velocity so that the riders do not slip from the wall. I know that tangential velocity equals V^2/r, but I am unsure how to get this only given the static friction and the radius. Can anyone help me?