Posted by **Anne** on Monday, February 28, 2011 at 5:14pm.

2 trains with 132Hz horns approach one another. The slower train has a speed of 25m/s. what is the speed of the fast train if an observer standing near the tracks between the trains hears a beat frequency of 5.2 Hz?

- Physics -
**Henry**, Wednesday, March 2, 2011 at 10:23pm
Fs = ((V + Vr) / (V + Vs))*Vo,

Fs = ((343 + O) / (343 + 25))132,

Fs = (343 / 368)132 = 123Hz = Frequency of slower train's horn,

Ff = 123 - 5.2 = 117.8 = Freq. of fast

train's horn.

Ff=((343 + 0) / (343 + Vs))132=117.8Hz.

45276 / (343 + Vs) = 117.8,

117.8(343 + Vs) = 45276,

343 + Vs = 45276 / 117.8 = 384.35,

Vs = 384.35 - 343 = 41.4m/s = Velocity

of suurce(fast train).

99

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