A) \[\frac{v}{\sqrt{2}}\]
B) \[\frac{V}{3}\]
C) \[\frac{V}{4}\]
D) \[\frac{V}{2}\]
Correct Answer: B
Solution :
When the sound is reflected from the cliff, it approaches the driver of the car. Therefore, the driver acts as an observer and both the source (car) and observer are moving. Hence, apparent frequency heard by the observer (driver) is given by \[f'=f\left( \frac{v+{{v}_{0}}}{v-{{v}_{0}}} \right)\] (i) where v = velocity of sound, \[{{v}_{0}}=\]velocity of car\[={{v}_{s}}\] Frequency of reflected sound heard by driver \[n'=n\left( \frac{v+{{v}_{O}}}{v-{{v}_{S}}} \right)\] It is given that \[n'=2n\] Hence, \[2n=n\left( \frac{v+{{v}_{car}}}{v-{{v}_{car}}} \right)\Rightarrow {{v}_{car}}=v/3\]You need to login to perform this action.
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