Physics Problem Help?

[匿名]

2017-02-22 3:53 pm

A car is traveling with a velocity magnitude of v1 eastward, parallel to a road next to a set of railroad tracks. Two trains are approaching each other, and they are both traveling v2 relative to the ground. Both trains blow their whistles, one after another, as they approach the car’s initial location. The whistles have a natural frequency f, and let the speed of sound in air to be v.

(a) Calculate the frequences f'E for the eastbound train and f'W for the westbound train, as heard by the driver of the car. Express your answer in terms of the following variables: v1, v2, f, and/or v.

回答 (1)

NCS

2017-02-22 9:01 pm

✔ 最佳答案

f = Fo•(V + Vr)/(V+Vs) ← Doppler
Vr +ve if rcvr moving toward src, Vs -ve if src moving toward rcvr
so we have simple substitution here.

f'E = f * (v - v1) / (v - v2)
f'W = f * (v + v1) / (v - v2)
as long as the car remains between both trains.

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