Solve Sound Waves Problem: Calculate Speed of Sound + Wind Velocity

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Homework Help Overview

The problem involves two observers, A and B, who are 1 km apart, and the effects of wind on the speed of sound as they observe gunshots fired from each other's locations. The time intervals between the flash and the sound of the gun are provided, and the goal is to calculate the speed of sound in air and the wind velocity component in the direction from A to B.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relevance of different formulas, questioning the applicability of frequency and wavelength relations. They explore the implications of the travel times and the distance between the observers, and some suggest defining the speeds of sound and wind as variables to create equations.

Discussion Status

Participants are actively engaging with the problem, questioning assumptions about distances and the relationships between the variables. Some guidance has been offered regarding the need for two equations to solve for the unknowns, but no consensus or resolution has been reached yet.

Contextual Notes

There is a noted lack of explicit information regarding the distances from the guns to the observers, leading to confusion about how to set up the problem. The discussion reflects the complexity introduced by the moving medium (wind) affecting sound propagation.

EmoHeartz
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Can someone help me with this question, I am stucked

A and B are two observers 1km apart . There is a steady wind blowing . When a gun is fired at A the time interval between the flash and report observed at B is 3.04s. When a gun is fired at B the time interval between the flash and report observed at A is 2.96s.
Calculate the valocity of sound in air and velocity component of wind in direction BA.

do i use the formula f=v/wavelength or velocity=distance/time?
 
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Think it through. How would the frequency/wavelength relation even be of any help? What speed would you put into it?

The problem is asking for the speed of sound and it gives you information about the travel times and the distance traveled. Which formula do you think would be helpful?

Once you decide that here's a hint:

The speed of sound relative to the ground must take into account that the fact that the sound is traveling through a medium that is itself moving.
 
but it did not give me the distance between the gun and A.
does it mean i use 1km?
 
"The gun is fired at A and the report is observed at B" ... therefore ...?
 
EmoHeartz said:
but it did not give me the distance between the gun and A.
does it mean i use 1km?

No, "at" does not mean "1 km away"! :smile:

Wavelength and frequency relations are useless here because you are not told either of those.

Let u be the speed of sound, v be the speed of the wind. Since wind is moving air and sound moves through the air, the net speed of sound, in the direction the wind is blowing, is u+ v. The net speed of sound, in the opposite direction, is u- v. Does that help?
 
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thanks..i think i understand now .but how do i find the velocity of the wind?
 
You have two unknowns, u and v. You need to come up with two equations that you need to solve simultaneously to figure out u and v together.

A has a gun, and B has a gun. A fires, B listens. Then B fires, A listens.
 

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