An amusement park ride consists of a large vertical cylinder that spins about its axis fast enough that any person inside is held up against the wall when the floor drops away (Fig. P6.65). The coefficient of static friction between person and wall is μs, and the radius of the cylinder is R. (a) Show that the maximum period of revolution necessary to keep the person from falling is T = (4π2Rμs/g)1/2. (b) Obtain a numerical value for T if R = 4.00 m and μs = 0.400. How many revolutions per minute does the cylinder make?