A source of sound of frequency $640 \mathrm{~Hz}$ is moving at a velocity of $\frac{100}{3} \mathrm{~m} / \mathrm{s}$ along a road, and is at an instant $30 \mathrm{~m}$ away from a point $A$ on the road (as shown in figure). A person standing at $O, 40 \mathrm{~m}$ away from the road hears sound of apparent frequency $v^{\prime}$. The value of $v^{\prime}$ is (velocity of sound $=340 \mathrm{~m} / \mathrm{s}$ )

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Aicharya · Accepted Answer

We know that, $ n^{\prime}=n\left[\frac{v}{v-v_s \cos 	heta}ight] $ Hence, $ \begin{aligned} n^{\prime} & =640\left[\frac{340}{340-\frac{100}{5}}ight] \ n^{\prime} & =640 	imes \frac{340}{320}=2 	imes 340 \ & =680 \mathrm{~Hz} \end{aligned} $

A source of sound of frequency $640 \mathrm{~Hz}$ is moving at a velocity of $\frac{100}{3} \mathrm{~m} /…

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