Walker, Halliday & Resnick — Waves-II: Problem 43

43 A sound wave of the form \(s = s_m \cos(kx - \omega t + \phi)\) travels at 343 m/s through air in a long horizontal tube. At one instant, air molecule A at \(x = 2.000\text{ m}\) is at its maximum positive displacement of 5.00 nm and air molecule B at \(x = 2.070\text{ m}\) is at a positive displacement of 2.00 nm. All the molecules between A and B are at intermediate displacements. What is the frequency of the wave?