According to einstein's special theory of relativity, the speed of light in a vacuum would be 3.0 108 m/s in which frames of reference? a. all frames of reference, regardless of acceleration b. frames of reference that are accelerating c. frames of reference that change velocity d. frames of reference that are not accelerating

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