High speed train sounding horn - Doppler effect

In summary, the conversation discusses finding the frequency of a sound as perceived by a person standing at a crossing when a high speed train is traveling at 41 m/s and the engineer sounds a warning horn with a frequency of 416 Hz. The equation used is f0=fs/(1-vs/v) and the correct answer is 366.6 Hz. The issue was that the sign in the denominator should have been positive instead of negative.
  • #1
conniechiwa
50
0
A high speed train is traveling at a speed of 41 m/s when the engineer sounds the 416 Hz warning horn. The speed of sound is 345 m/s. What is the frequency of the sound as perceived by a person standing on at the crossing when the train is leaving?

I used the equation: f0=fs/(1-vs/v)
f0=416 Hz / 1-(41 m/s / 345 m/s)
f0=366.6

I'm not sure what I'm doing wrong... =(
 
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  • #2
You want to find the observed frequency for when the train is moving away from the observer. When the source is moving away from the observer, the sign in the denominator is positive, not negative. That is you problem.
 
  • #3
oh okay thanks!
 
  • #4
No problem. :smile:
 

What is the Doppler effect?

The Doppler effect is a phenomenon in which the frequency of a wave changes when there is relative motion between the source of the wave and the observer.

How does the Doppler effect apply to high speed train sounding horns?

The Doppler effect is the reason why the sound of a train horn changes as it approaches and passes by. As the train moves towards the observer, the sound waves are compressed, resulting in a higher frequency and a higher pitch. As the train moves away, the sound waves are stretched, resulting in a lower frequency and a lower pitch.

What factors affect the intensity of the sound heard from a high speed train horn?

The intensity of the sound heard from a high speed train horn is affected by several factors, including the speed of the train, the distance between the train and the observer, and the direction and strength of the wind.

How does the Doppler effect impact the safety of high speed trains?

The Doppler effect can affect the perception of sound for both the train operator and other individuals near the tracks. It is important for train operators to be aware of the Doppler effect and make adjustments to ensure the safety of passengers and pedestrians.

Are there any applications of the Doppler effect in other areas besides high speed trains?

Yes, the Doppler effect has many applications in science and technology, including radar and sonar technology, medical imaging, and astronomy. It is also used in everyday devices such as speed guns and weather radars.

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