4. a tuning fork is held over a resonance tube, and resonance occurs when the surface of the water is 12 cm below the top of the tube. resonance occurs again when the water is 34 cm below the top of the tube. if the air temperature is 23 ˚c, find the frequency of the tuning fork.

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