Physics - Sound Wave Question with Solution | TestHub

Let listener go from $A\to B$ with velocity $(\mu ).$
And the apparent frequency of sound from source $A$ by listener using Doppler's effect, $$n^{\prime }=n\left(\frac{v-v_o}{v+v_s}\right)\Rightarrow n^{\prime }=680\left(\frac{340-u}{340+0}\right)$$ The apparent frequency of sound from source $B$ by listener $$n^{\prime \prime }=n\left(\frac{v+v_o}{v-v_s}\right)=680\left(\frac{340+u}{340-0}\right)$$ Listener hear 10 beats per second. $$\begin{array}{l}\text{ Hence, }{n}^{\prime \prime }-n^{\prime }=10\\ \Rightarrow 680\left(\frac{340+u}{340}\right)-680\left(\frac{340-u}{340}\right)=10\\ \Rightarrow 2(340+u-340+u)=10\\ \Rightarrow u=2.5{\mathrm{ms}}^{-1}\end{array}$$