Question

A source emits sound with a frequency of 860 Hz. It is moving at 20.0 m/s toward a stationary reflecting wall. If the speed of sound is 343 m/s, what frequency does an observer riding with the source hear

Answer 1

Answer:

Explanation:

f = 860 Hz

velocity of  source, vs = 20 m/s

velocity of sound, v = 343 m/s

use the formula of doppler's effect

the frequency reflected from the wall is

$f' = \frac{v}{v+ v_{s}}\times f$

$f' = \frac{343}{343+20}\times 860$

f' = 812.62 Hz

Frequency heard by the observer

$f'' = \frac{343}{343-20}\times 812.62$

f'' = 862.93 Hz