Question

a car with a horn of frequency 620 hz travels towards a large wall with a speed of 20 m/s. if the velocity of sound is 330 m/s. the frequency of echo of sound of horn as heard by the driver is :

Answer 1

Answer:660Hz

Explanation:

when source is approaching the observer then use + above and - below in the formula. when source is moving away from observer then use - above and + below

Answer 2

Hey Dear,

This problem is in relation to Doppler effect in sound.

◆ Answer -

Frequency of echo of sound of horn as heard by the driver is 700 Hz.

◆ Explanation -

When sound of car horn reaches the wall, frequency of the sound is -

ν1 = (ν × c) / (c - v)

v1 = (620 × 330) / (330-20)

v1 = 660 Hz

When sound of echo from wall returns to car, frequency of sound will be -

ν2 = ν1 × (c + v) / c

ν2 = 660 × (330 + 20) / 330

v2 = 700 Hz

Therefore, frequency of echo of sound of horn as heard by the driver is 700 Hz.

Hope this helped you.