Question

In a certain amusement-park ride, riders stand with their backs against the wall of a spinning vertical cylinder. The floor falls away and the riders are held up by friction. If the radius of the cylinder is 4.2 m, find the minimum number of revolutions per minute to prevent riders from dropping when the coefficient of static friction between a rider and the wall is 0.41.

Answer 1

.41 omega^2 r = g

omega^2 = 9.81/(.41*4.2) = 5.7
omega = 2.39 radians/second

2.39 radians/second *30 seconds/min *1 rev/2 pi radians = 11.3 rpm

Answer 2

With that answer, it's right, but there's 60 seconds per min