A light wave traveling through medium 1 strikes a boundary with medium 2 at
a 45° angle. The light then enters the second medium and refracts away from
the boundary. What could the two mediums be?
A. Medium 1: water
Medium 2: air
B. Medium 1: glass
Medium 2: water
C. Medium 1: glass
Medium 2: diamond
D. Medium 1: diamond
Medium 2: air

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