# A source of frequency 50Hz is moving towards an observer with a deceleration of 2m/s^2. If its initial speed is 20m/s, what will be the maximum frequency heard by the observer?

Q:

A source of frequency 50Hz is moving towards an observer with a deceleration of 2m/s^2. If its initial speed is 20m/s, what will be the maximum frequency heard by the observer? Initial distance between source and observer is 100m. Speed of sound = 330m/s.

(a) 47.14Hz

(b) 0

(c) 53.22Hz

(d) 53.03Hz

I got this question in homework.

This intriguing question originated from Waves in portion Waves of Physics – Class 11

Correct option is (c) 53.22Hz

Best explanation: Apparent frequency only depends on velocity and not the distance between source and observer.                                                                                                                                                                               So, maximum frequency will be heard when speed is maximum, which is at the start.                                             F = 50(330)/(330-20)

= 53.22Hz.