A train running at 108 km h-1 towards east whittles at a dominant frequency of 500 Hz. Speed of sound in air is 340 m/s, What frequency will a passenger sitting near the open window hear 7 (b) What frequency will a person standing near the track hear whom the train has just passed? (c) A wind start blowing towards east at a speed of 36 km h-1. Calculate the frequencies heard by the passenger in the train and by the person standing near the track.

(a) The frequency can be calculated by,



Here,


f0=500Hz


v0= 108 km/h =30m/s


vs=108 km/h = 30m/s


v=340m/s




(b)


For a person near the track,



f0=500Hz


vs= 108 km/h =30m/s


v=340m/s




(c)


500 Hz by the passenger and 458 by the person near the track


Introduction of the speed of the medium changes both the source and observer speed in the equation. For the passenger onboard



And



Hence



For the person outside,




Hence





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