In a certain material, a beam of monochromatic light (f=5.09 × 10^14 Hz) has a speed of 2.04× 10^8 meters per second. The material could be Question 14 options:

crown glass (n=1.52)

flint glass (n=1.66)

glycerol (n=1.47)

water (n=1.33)

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm