A car sounding a horn of frequency 1000 ~Hz passes a stationary observer. The ratio of frequencies of the horn noted by the observer before and after passing the car is 11: 9 . If the speed of sound is ' v ', the speed of the car is

Step-by-step solution

Frequency of a source moving towards a stationary listener is n _ b = ( v v - v _ s ) n Frequency of a source moving towards a stationary listener is n _ a = ( v v + v _ s ) n Taking the ratio n _ b n _ a = ( v + v _ s v - v _ s ) aligned & 11 9 = ( v + v _ s v - v _ s ) & 11 v +11 v _ s =9 v -9 v _ s & 2 v =20 v _ s & v _ s = 1 10 v aligned