Halliday, Resnick & Walker — Waves–II: Problem 14

Figure 17.8 shows the output from a pressure monitor mounted at a point along the path taken by a sound wave of a single frequency traveling at 343 m/s through air with a uniform density of \(1.21 \text{ kg/m}^3\). The vertical axis scale is set by \(\Delta p_s = 4.0 \text{ mPa}\). If the displacement function of the wave is \(s(x, t) = s_m \cos(kx - \omega t)\), what are (a) \(s_m\), (b) \(k\), and (c) \(\omega\)? The air is then cooled so that its density is \(1.35 \text{ kg/m}^3\) and the speed of a sound wave through it is 320 m/s. The sound source again emits the sound wave at the same frequency and same pressure amplitude. What now are (d) \(s_m\), (e) \(k\), and (f) \(\omega\)?