A police car horn emits a sound at a frequency $240 Hz$ when the car is at rest. If the speed of the sound is $330 m/s$, the frequency heard by an observer who is approaching the car at a speed of $11 m/s,$ is ... $Hz$
Medium
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(a) Frequency heard by the observer
$n' = n\,\left( {\frac{{v + {v_0}}}{v}} \right) = 240\,\left( {\frac{{330 + 11}}{{330}}} \right) = 248Hz.$
$n' = n\,\left( {\frac{{v + {v_0}}}{v}} \right) = 240\,\left( {\frac{{330 + 11}}{{330}}} \right) = 248Hz.$
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