Physics - Sound Wave Question with Solution | TestHub

The reflected sound appears to propagate in a direction opposite to that of moving engine. Thus, the source and the observer can be presumed to approach each other with same velocity. $v^{\prime }=\frac{v\left(v+v_o\right)}{\left(v-v_s\right)}$ $=v\left(\frac{v+v_s}{v-v_s}\right)\left(\because v_o=v_s\right)$ $\Rightarrow v^{\prime }=1.2\left(\frac{350+50}{350-50}\right)$ $=\frac{1.2\times 400}{300}$ $=1.6\mathrm{kHz}$