A speeding motorcyclist sees a traffic jam ah | vedclass

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(C) The speed of the motorcyclist (observer) is $v_o = 36\, km\, h^{-1} = 36 	imes \frac{5}{18} = 10\, m s^{-1}$.Since the motorcyclist is moving tow

Vedclass · Accepted Answer

$1412$

Vedclass · Answer

(C) The speed of the motorcyclist (observer) is $v_o = 36\, km\, h^{-1} = 36 	imes \frac{5}{18} = 10\, m s^{-1}$.Since the motorcyclist is moving towards the source (car),the observer's velocity is taken as positive.The speed of the car (source) is $v_s = 18\, km\, h^{-1} = 18 	imes \frac{5}{18} = 5\, m s^{-1}$.Since the source is moving away from the observer,the source's velocity is taken as positive.The speed of sound is $v = 343\, m s^{-1}$.The frequency of the source is $f_0 = 1392\, Hz$.Using the Doppler effect formula for frequency heard by the observer,$f' = f_0 \left( \frac{v + v_o}{v + v_s} ight)$,$f' = 1392 \left( \frac{343 + 10}{343 + 5} ight)$,$f' = 1392 \left( \frac{353}{348} ight)$,$f' = 4 	imes 353 = 1412\, Hz$.

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