Question
 A source and an observer are approaching one another with velocity $4 m / s$. If the true frequency is $1200 Hz$ , deduce the observed frequency under the following conditions:
i. All velocity is in the source alone.
ii. All velocity is in the observer alone.
Take the velocity of sound waves in air to be $340 ms^{-1}$.

Answer

  1. $\text{v}'=\text{v}\Big(\frac{\nu}{\nu-\nu_\text{s}}\Big)=1200\Big(\frac{340}{336}\Big)\text{ft}$
$=1214.28\text{Hz}$
  1. $\text{v}'=\text{v}\Big(\frac{\nu+\nu_0}{\nu_0}\Big)=1200\Big(\frac{344}{340}\Big)$
$=1214.11\text{Hz}$

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