Wall of Death in amusement park - Find number of revolutions

[BeatTheRuckus]

Here is the question:
The Wall of Death in an amusement park is comprised of a vertical cylinder that can spin around the vertical axis. The radius of the cylinder is 3.5 m and the coefficient of static friction between the rider and the wall is 0.32. Find the minimum number of revolutions per minute necessary so that the riders do not slip down the wall (enter rev/min).
I think I am doing it right, but I do not know

 

[mgb_phys]

The vertical force you have to overcome is the riders weight.
The friction force is the normal force (force outward) * coef friction.

You just need to know the outward (centrifugal) force on a spinning object.

 

[BeatTheRuckus]

the thing is, I do not know the riders' weight/mass, or velocity

 

[mgb_phys]

When you write down the equations something happens to the mass...
You do know the riders velocity, you have the radius and the rev/second - but you don't need it. Start by looking up the equation for centrifugal force