To determine the frequency heard by the train, we need to take into account the Doppler effect. The Doppler effect is the change in frequency of a wave (in this case, sound) perceived by an observer when there is relative motion between the source of the sound and the observer.
The formula for the Doppler effect with sound is given by:
f' = f * (v + Vr) / (v + Vs)
Where:
f' = frequency heard by the observer
f = frequency of the source (in this case, the horn)
v = speed of sound in air (approximately 343 m/s)
Vr = speed of the receiver (in this case, the train)
Vs = speed of the source (in this case, the speed of the train)
We know that the frequency heard by the passengers at the station (f') is 373 Hz and the speed of sound in air (v) is approximately 343 m/s.
Let's rearrange the equation to solve for the speed of the train (Vr):
Vr = (f' - f * (v + Vs)) / f
Substituting the given values:
Vr = (373 - 343 * (343 + 45)) / 343
Calculating the result:
Vr = (373 - 343 * 388) / 343
Vr = (373 - 133484) / 343
Vr = -133111 / 343
Vr ≈ -388.2 m/s
The negative sign indicates that the train is moving away from the stationary passengers at the station.
Therefore, the frequency heard by the train is lower than the frequency heard by the passengers at the station.
As a train pulls out of the station going 45 m/s it blasts its horn, what is the frequency heard by the train if the passengers still at the station are hearing 373 Hz?
gr 11 physics
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1 answer