What beat frequency will the observer detect?

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Homework Help Overview

The problem involves two trains emitting whistles at the same frequency of 282 Hz, with one train at rest and the other moving away from an observer. The focus is on determining the beat frequency detected by the observer.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of the listener behind formula and explore the calculations for the frequencies perceived by the observer for both trains. There are questions about the correctness of the initial calculations and the process of determining the beat frequency.

Discussion Status

Some participants have provided calculations and reached a frequency difference, while others have prompted for more detailed workings. There is a recognition of the calculations leading to a potential answer, but no consensus on the correctness of the final result.

Contextual Notes

Participants are navigating through the application of formulas related to sound frequency and motion, with some expressing confusion about the results and seeking further assistance on related topics.

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Homework Statement


Two trains emit whistles of the same frequency, 282 Hz. If one train is at rest and the other is traveling at 45 km/h away from an observer at rest, what beat frequency will the observer detect?



Homework Equations





The Attempt at a Solution



I used listener behind formula and got an answer of 544 Hz because i doubled the Frequency source. The answer is wrong, please help me!Thanks!
 
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Why don't you show your working out.
 
While i was waiting i looked over it again and this is what i did for another answer i got

F(listener behind)=F(of source) [v/v+v(source)]

I did one for each since there are two trains.
For the train on rest, i did F(listner behind)=282*[343/(343+0)] which is 282 Hz

For the train going 12.5 m/s i did, F(lb)=282*[343/(343+12.5)] and got 272 Hz

So then i subtracted 282-272 and got 10 Hz, is this the answer?
 
That's the one.
 
Thanks! I'm also having major trouble with an intensity problem, can you help me with that? Thanks!
 

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