# physics

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A mag lev train traveling at 180 m/s towards a rail way crossing sounds its horn with a wavelength of 0.20 m. What is the frequency of sound that people waiting at the rail way crossing hear?

• physics -

L = V/Fs.
Fs = V/L = 343/0.2 = 1715 cy/s = 1715 Hz.= The frequency of the source.

Fr = ((V+Vr)/(V-Vs))*Fs.
Fr = ((343+0)/(343-180))*1715 = 3609 Hz.
= Freq. received or heard by the people.

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