The threshold of hearing is defined as the minimum discernible intensity of the sound. It is approximately 10^-12 W/m^2 . Find the distance from the car at which the sound from the stereo can still be discerned. Assume that the windows are rolled down and that each speaker actually produces 0.06 W of sound, as suggested in the last follow-up comment.
2007-12-05 19:17:58 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Assuming the sound is radiated uniformly in all directions, the power from the speaker is distributed over the surface of a sphere of radius r, where r is the distance from the speaker. The sound intensity is watt/m^ and is found by dividing the total speaker power W by the surface area of the sphere, 4πr^2.
I = W/(4πr^2)
Set I to be 10^-12, W = 0.06watt (if there are more than one speaker, multiply this times the number of speakers), and solve for r
2007-12-05 19:24:34 · answer #1 · answered by gp4rts 7 · 0⤊ 0⤋