[SOLVED] sound intensity - the threshold of pain 1. The problem statement, all variables and given/known data You are investigating the report of a UFO landing in an isolated portion of New Mexico, and encounter a strange object that is radiating sound waves uniformly in all directions. Assume that the sound comes from a point source and that you can ignore reflections. You are slowly walking toward the source. When you are 7.5 m from it, you measure its intensity to be 0.11 W/m^2. An intensity of 1.0W/m^2 is often used as the "threshold of pain". How much closer to the source can you move before the sound intensity reaches this threshold? 2. Relevant equations I1/I2 = r2^2/r1^2 3. The attempt at a solution r2 = r1(I1/I2)^1/2 = (7.5)(.11)^1/2 = 2.5m - incorrect done another way r2 = [(r1)^2(I1/I2)]^1/2 = (56m^2(.11))^1/2 = 2.5m - incorrect I dont' know the equations aren't working for me, any help is appreciated.