Answer:
[tex]0.0089 W/m^2[/tex]
Explanation:
The intensity of a sound wave is given by
[tex]I=\frac{P}{A}[/tex]
where
P is the power of the wave at the source
A is the area over which the sound wave propagates
In this problem, we have
P = 70.0 W is the power
We want to know the intensity at a distance of r = 25.0 m from the orchestra, so since the sound waves propagates radially, we must consider a spherical surface of radius r, so the area is
[tex]A=4\pi r^2 = 4\pi (25.0 m)^2=7850 m^2[/tex]
Therefore, the intensity of the wave is
[tex]I=\frac{70 W}{7850 m^2}=0.0089 W/m^2[/tex]
