Question

An engine running at speed v/10 sounds a whistle of frequency 600 Hz. A passenger in a train coming from the opposite side at speed v/15 experiences this whistle to be of frequency f. If v is speed of sound in air and there is no wind, f is nearest to

• A. 711 Hz
• B. 630 Hz
• C. 580 Hz
• D. 510 Hz
  

Answer 1

The correct option is A 711 Hz

As the source and the observer are approaching one another, so n’ would be larger.
$f=\left(\frac{v+\frac{v}{15}}{v-\frac{v}{10}}\right)600=711Hz$