question_answer

Two cars A and B are moving away from each other in opposite directions. Both the cars are moving with a speed of  with respect to the ground. If an observer in car A detects a frequency 2000 Hz of the sound coming from car B, what is the natural frequency of the sound source in car B? (speed of sound in air ) :- [JEE Main 9-4-2019 Afternoon]

A) 2250 Hz

B) 2060 Hz

C) 2150 Hz

D) 2300 Hz

Correct Answer: A

Solution :

[a]

20m/s

Applying Doppler effect for sound

is taken when approaching each other)