Friction, centripetal force, gravity, and velocity

[katie beisel]

Homework Statement

Rebecca goes on a popular ride at an amusement park that involves a cylinder rotating on a vertical axis, with a radius of 6.20 m. Rebecca stands inside, with her back against the wall of the cylinder. The ride rotates and presses Rebecca against the wall of the cylinder, and when she reaches a speed v, the floor of the ride drops so that she can no longer stand on it. The coefficient of static friction between the wall and Rebecca's clothing is 0.820. What should Rebecca's minimum speed v be when the floor is lowered, so that she does not fall?

Homework Equations

The Attempt at a Solution

I've tried a lot of different equations but none of them give me the right answer
g = v2/r
9.8 = v2/6.2
60.76 = v2
v = 7.79
the correct answer is 8.61

 

[cnh1995]

Draw an FBD showing all the forces acting on Rebecca's body. That way you can set up an equation with all the known quantities.