A train is moving with a speed of $100\ \text{km/h}$. Now, suddenly it blows horn with a frequency of $100\…
A train is moving with a speed of $100\ \text{km/h}$. Now, suddenly it blows horn with a frequency of $100\ \text{Hz}$. If speed of sound in air is $330\ \text{ms}^{-1}$, then find the apparent frequency heard by a passenger sitting in the train.
Solution
Sol. Here, speed of the passenger (observer) is same as the source (train). Therefore, no Doppler’s effect will be observed. Thus, apparent frequency heard by the passenger, $f' = f = \text{actual frequency of horn} = 100\ \text{Hz}$
Answer: $100$ Hz