power output of 87 W. At what distance will the decibel reading be 120 dB, which is noise level of a loud indoor rock concert

r = 2.63 m

Explanation:

To find the distance at which the sound level is 120dB, you first calculate the intensity of the sound. You use the following formula:

          (1)

β: sound level = 120dB

I: intensity of the sound

Io: threshold of hearing = 10⁻12W/m^2

You solve the equation (1) for I and replace the values of all parameters:

Next, you use the following formula for the power of the sound with intensity I, and you solve for r:

r: distance at which the sound level is 120dB

P: power of the sound = 87W

I: intensity of the sound = 1W/m^2

You replace the values of I and P for calculating r:

The distance is at 2.63m from the source of the soundr = 2.63m

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