Question

If a train approaches you (sitting in the bench ) at a velocity of 35 m/s, what frequency will you hear as it sounds its whistle at 188 Hz? speed of sound= 345 m/sA) 188 HzB) 170.7 HzC) 209.2 HzD) 202.7 Hz

Answer 1

Given:

The speed of the train is,

`v_s=35\text{ m/s}`

The actual frequency of the whistle is,

`f=188\text{ Hz}`

The speed of sound in air is,

`v=345\text{ m/s}`

To find:

The frequency heard by the observer

Step-by-step explanation:

The apparent frequency when the train approaches the observer is given by,

`\begin{gathered} f_(apparent)=f(v)/(v-v_s) \\ =188*(345)/(345-35) \\ =188*(345)/(310) \\ =209.2\text{ Hz} \end{gathered}`

Hence, the frequency heard by you is 209.2 Hz.