First slide

Speed of wave

Question

Two factories are sounding their sirens at 800 Hz. A man goes from one factory to the other at a speed of 2 m/s. The velocity of sound is 320 m/s. The number of beats heard by the person in one second will be

Easy

A

2
B

4
C

8
D

10

Solution

When the man is approaching to a factory
$n^{'} = (\frac{v + v_{o}}{v}) n = (\frac{320 + 2}{320}) 800 = (\frac{322}{320}) 800 When the man is going away from the factory n^{''} = (\frac{v - v_{0}}{v}) n = (\frac{320 - 2}{320}) 800 = (\frac{318}{320}) 800 n^{'} - n^{''} = (\frac{322 - 318}{320}) 800 = \frac{4 \times 800}{320} = 10 Hz$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App