A man is travelling in a train towards the station with a speed of 50 ms - 1 . Calculate the apparent…
A man is travelling in a train towards the station with a speed of 50 ms - 1 . Calculate the apparent frequency heard by him of a whistle which is blown at the station with a frequency 200 Hz. Velocity of sound in air is 350 ms - 1.
Solution
Sol. In this case, observer is moving and source is at rest.
Therefore, apparent frequency heard by the observer,
$f' = \left(\frac{v + v_o}{v}\right) f = \left(\frac{350 + 50}{350}\right) \times 200$
$= \frac{400}{350} \times 200 = 228.57\ \mathrm{Hz}$
Answer: $228.57 \mathrm{Hz}$