Question

A source of sound of frequency 252 Hz is moving
rapidly towards a wall with a velocity of 50 m/s. The
speed of sound is 350 m/s. If the observer is in
between the wall and the source, then frequency of
the beats heard will be
(1) 7.8 Hz (2) 6.9 Hz
(3) 5.4 Hz (4) Zero

Answer 1

Answer:

see the attachment for solution

the sound from source will hit the wall,the observer hears the sound as it comes from wall with same speed (in this case 50m/s) put sign is negative