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 i

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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

TestHub · Accepted Answer

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

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