A barking dog delivers about 1.0 mW of power, which is assumed to be

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Homework Help Overview

The discussion revolves around calculating the intensity level in decibels of sound produced by a barking dog, which delivers approximately 1.0 mW of power uniformly in all directions. Participants are tasked with determining the intensity at a distance of 5.00 m from the source, using the threshold of human hearing as a reference.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between power, area, and intensity, referencing the formula I=P/A, where A is the surface area of a sphere. There are attempts to convert power from milliwatts to watts and questions about how to apply logarithmic formulas for decibels. Some participants express confusion about connecting the equations to the variables provided in the problem.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and attempting to clarify their understanding of the relevant equations. Some guidance has been offered regarding the setup of the problem, but there is still a lack of consensus on the approach to take.

Contextual Notes

Participants are grappling with the conversion of units and the implications of spreading power over a larger area as sound waves propagate. The problem context includes the threshold of human hearing, which is a critical factor in determining intensity levels.

chemistrymole
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Homework Statement



A barking dog delivers about 1.0 mW of power, which is assumed to be uniformly distributed in all directions. What is the intensity level in decibels at a distance 5.00 m from the dog? The threshold of human hearing is 1.0 × 10-12 W/m2.

Homework Equations



I=P/A A is 4pi(r^2)

The Attempt at a Solution



The only part I am missing is converting the 1 mW to something else so I can plug in the equation above. I tried the 10*log(xxxxxxxx) formula no luck.
 
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chemistrymole said:

Homework Statement



A barking dog delivers about 1.0 mW of power, which is assumed to be uniformly distributed in all directions. What is the intensity level in decibels at a distance 5.00 m from the dog? The threshold of human hearing is 1.0 × 10-12 W/m2.

Homework Equations



I=P/A A is 4pi(r^2)

The Attempt at a Solution



The only part I am missing is converting the 1 mW to something else so I can plug in the equation above. I tried the 10*log(xxxxxxxx) formula no luck.

Homework Statement


Homework Equations


The Attempt at a Solution


The power all goes through each spherical surface surrounding the dog. If the sphere has a surface area of 1m^2, then the power flux density is 1.0mW/m^2. If the sphere is a little bigger, and has a surface area of 2m^2, then the power flux density 1.0mW/2m^2 = 0.5mW/m^2.

Does that help?
 
No still lost and confused.

Can someone please explain equations further I am not seeing how it connects to the variables given in the question.
 
chemistrymole said:
No still lost and confused.

Can someone please explain equations further I am not seeing how it connects to the variables given in the question.

As the sound waves of the bark radiate out from the dog, the 1mW of power (P) gets spread over a progressively larger area (A). At a distance of 5m, what area is it spread over?
 
haruspex said:
As the sound waves of the bark radiate out from the dog, the 1mW of power (P) gets spread over a progressively larger area (A). At a distance of 5m, what area is it spread over?

Do I have to convert 1 mW to W?

So would my setup be I = 1/pir^2?

I think my main formula template is I=P/A
 
Thanks everyone I found a solution that shows me how to do it. Now I actually understand it and know how the units work.
 

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