A and B are two sources generating sound waves.a listener is situated at c.the frequency of source A is 500 hz. A , now moves with a velocity of 4m/s towards c .the number of beats heard at c is 6.when A moves away from c at a speed of 4m/s , the number of beats heard at c is 18.the speed of sound is 340m/s.the frequency of source at b is what??

let the frequence of source at B = v

 

frequence of source A heard at C when it is coming close to C is = 340/(340-4) * 500 = 506 Hz

thus beats produced, 6 = 506-v

 

frequency of source A heard at C, when it is receeding from C = 340/(340+4) *500 = 494 Hz

thus beats produced in this case, 18 = v - 494

 

solving we can get the frequency of the source B