Question 96: Waves

Question

A train blowing a whistle of frequency 320 Hz approaches an observer standing on the platform at a speed of 66 m/s. The frequency observed by the observer will be (given speed of sound = 330 ms$$^{-1}$$) __________ Hz.

Accepted Answer

$f=f_{0}\left(\frac{v}{v-v_{s}}ight)$
$$
\begin{aligned}
& f=320\left(\frac{330}{330-66}ight) \\
& =320 	imes \frac{330}{264} \\
& =400 \mathrm{~Hz} .
\end{aligned}
$$

Waves

A train blowing a whistle of frequency 320 Hz approaches an observer standing on the platform at a speed of 66 m/s. The frequency observed by the observer will be (given speed of sound = 330 ms$^{-1}$) __________ Hz.

Choose the correct answer: