Physics - Sound Wave Question with Solution | TestHub

Concept Source is moving away from a stationary observer $\therefore {\mathrm{f}}^{\prime }=\mathrm{f}\left(\frac{\mathrm{v}}{\mathrm{v}+{\mathrm{v}}_{\mathrm{s}}}\right)$ Where, $f$ is the true frequency $v$ is the speed of sound and $v_s$ is the speed of source. Given, $\mathrm{f}=1152,\mathrm{v}=340\mathrm{m}/\mathrm{s}$ $\text{ and }{\mathrm{v}}_{\mathrm{s}}=\frac{72\times 10^3}{3600}\mathrm{m}/\mathrm{s}=20\mathrm{m}/\mathrm{s}$ $\therefore$ the apparent frequency ${\mathrm{f}}^{\prime }=1152\frac{\times (340)}{(340+20)}\mathrm{Hz}=1088\mathrm{Hz}$