Two Sources A And B Are Sounding Notes Of Frequency 680 Hz. A Listener Moves From A To B With A Constant Velocity u. If The Speed Of Sound Is 340 Ms –1, What Must Be The Value Of u so That He Hears 10 Beats Per Second?

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Question

Two sources A and B are sounding notes of frequency 680 Hz. A listener moves from A to B with a constant velocity u. If the speed of sound is 340 ms –1, what must be the value of u so that he hears 10 beats per second?

Solution

Correct option is

2.5 ms–1

 

The listener moves away from A and approaches B. Hence the apparent frequencies are

                       

 It is given that V2 – V1 = 10. V = 340 ms–1 andV = 680 Hz.   

Substituting these values we get 

            

  

Testing

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