A loudspeaker at a rock concert generates a sound that has an intensity level equal to 1.00x10^-2 W/m^2 at 20.0 m and has a frequency of 1.00 kHz. Assume that the speaker spreads its energy uniformly in three dimensions. (Hint: Intensity: I = P/A. In three dimensions, the surface area of a sphere is A = 4πr^2)
(a) What is the total acoustic power output of the speaker?
(b) At what distance will the sound intensity be at the pain threshold of 1.00 W/m^2?
(c) What is the sound intensity at 30.0 m?