Two trains A and B are moving towards each ot | vedclass

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(C) The apparent frequency due to the Doppler effect when both the observer $O$ and the source $S$ are approaching each other is given by the formula:

Vedclass · Accepted Answer

$700$

Vedclass · Answer

(C) The apparent frequency due to the Doppler effect when both the observer $O$ and the source $S$ are approaching each other is given by the formula:$f' = f \left( \frac{v + v_o}{v - v_s} ight)$ ... $(i)$Here,the speed of the observer (Train $B$),$v_o = 36 \ km/h = 36 	imes \frac{5}{18} \ m/s = 10 \ m/s$.The speed of the source (Train $A$),$v_s = 72 \ km/h = 72 	imes \frac{5}{18} \ m/s = 20 \ m/s$.The speed of sound in air,$v = 340 \ m/s$.The actual frequency of the source,$f = 640 \ Hz$.Substituting these values into equation $(i)$:$f' = 640 \left( \frac{340 + 10}{340 - 20} ight)$$f' = 640 \left( \frac{350}{320} ight)$$f' = 640 	imes 1.09375 = 700 \ Hz$.Therefore,the frequency heard by the passenger in Train $B$ is $700 \ Hz$.

Two trains $A$ and $B$ are moving towards each other with speeds $72 \ km/h$ and $36 \ km/h$ respectively. The train $A$ whistles at $640 \ Hz$ frequency. Before the trains meet,the frequency of sound heard by a passenger in Train $B$ is (Speed of sound in air $= 340 \ m/s$). (in $Hz$)

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