A siren emitting sound of frequency $500 \;Hz$ is going away from a static listener with a speed of $50\, m/sec$. The frequency of sound to be heard, directly from the siren, is .... $Hz$
AIIMS 1999, Medium
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(a) $n' = n\,\left( {\frac{v}{{v + {v_S}}}} \right) = 500 \times \left( {\frac{{330}}{{300 + 50}}} \right) = 434.2Hz$
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