Minimum Coefficient of Friction

[mohabitar]

In a classic carnival ride, patrons stand against the wall in a cylindrically shaped room. Once the room gets spinning fast enough, the floor drops from the bottom of the room! Friction between the walls of the room and the people on the ride make them the “stick” to the wall so they do not slide down. In one ride, the radius of the cylindrical room is R = 7.4 m and the room spins with a frequency of 21.4 revolutions per minute.

Here are the questions I got right:
What is the minimum coefficient of friction needed between the wall and the person?
Answer: .26

Here are the ones I need help with:

If a new person with mass 108 kg rides the ride, what minimum coefficient of friction between the wall and the person would be needed?

Well, coefficients of friction depend on properties of objects, not size or weight, so the answer to this one would be the same, .26 correct?

To be safe, the engineers making the ride want to be sure the normal force does not exceed 2.3 times each persons weight - and therefore adjust the frequency of revolution accordingly. What is the minimum coefficient of friction now needed?

As for that one, would this not be just the same case? Coefficient of friction only depends on properties? Well all the properties are staying the same, just the frequency of revolution changes. So the answer would be .26 again, or am I looking at this wrong?

 

[housemartin]

yes, coefficient of friction depend on properties of two "interacting" objects. But what force of friction depends on?
Besides, did you get first answer without knowing mass of the person?