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Question: Answered & Verified by Expert
With what velocity should an observer approach a stationary sound source, so that the apparent frequency of sound should appear double the actual frequency? ( is velocity of sound).
PhysicsWaves and SoundKCETKCET 2008
Options:
  • A $\frac{v}{2}$
  • B $3 \mathrm{v}$
  • C $2 \mathrm{~V}$
  • D None of these
Solution:
1996 Upvotes Verified Answer
The correct answer is: None of these
By using
$$
\begin{gathered}
v^{\prime}=v\left[\frac{v-v_{0}}{v-v_{s}}\right] \\
2 v=v\left[\frac{v-v_{0}}{v-0}\right]
\end{gathered}
$$
$\Rightarrow \quad \mathrm{v}_{\mathrm{o}}=-\mathrm{v} .$
Negative sign indicates that observer is moving opposite to the direction of velocity of sound.

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