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cepheid

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## The Attempt at a Solution

For the second part: What is the sound power of the loudspeaker at a distance of 1m?

I= P/ 4πr² → P= 4πr²*I

P= 1.256 x 10^-11 W

I don't think this is correct, because I = 10

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nasu

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I =C f^2*rho*A^2

Where rho is density, f is frequency, A is the amplitude (maximum displacement).

C is a constant, I don;t remember the exact form. It shoul be in your book.

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cepheid

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Probably not! So you just used the formula that nasu gave you? The point of what both of us were saying to you was that you should look it up in your book or notes. He didn't give you the exact form because wasn't 100% sure of it, and he specifically said that you should_{So, the intensity of the tiny speaker is: I= C*f²*ρ*A² I= 340 m/s * (1000 Hz)² * 1.2 kg/m³ * (0.0000005 m) ² I= 1.02 x 10^-6 W/m² Is this correct? }

As for the second part, calculating the distance at which the sound becomes inaudible, you already *know* how intensity varies with distance. You wrote the equations for this in your first post.

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nasu

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Depends what you used for x._{So, if I understood the relationship correctly, this is how to calculate the distance: I= x/r² → r= sqrt(x/I) r= 22.3 m }

Here x should be the power of the source. It is NOT the intensity that you calculated.

You don't really need this power.

You know the intensity at 1m and the intensity at some unknown distance r.

The ratio between intensities is same as the inverse ratio of the distances squared.

You coul also calculate the power of the source and go for there. Maybe this is what you have done?

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