Find the intensity of a sound wave from 1km away, with a power of 20kw

Explanation:

The intensity of a wave propagating in all directions from a source is given by the inverse square law:

where

I is the intensity of the wave at a distance r from the source

P is the power of the source

r is the distance from the source

The formula arises from the fact that the wave propagates over the surface of a sphere of radius r, so over a surface of (surface of a sphere).

In this problem, we have:

is the power of the source of the sound wave

is the distance at which we want to calculate the intensity

Therefore, the intensity of the sound wave is:

like poles repel so keep pushing north to north and repels funny to see this