posted by Coreen .
Speakers A and B are vibrating in phase. They are directly facing each other, are 7.4 m apart, and are each playing a 72.0 Hz tone. The speed of sound is 343 m/s. On the line between the speakers there are three points where constructive interference occurs. What are the distances of these three points from speaker A?
Calculate wavelength. When the difference in distances from each speaker are multiples of wavelength, construtcive interference occurs. For instance, if the wavelenght were 1 meter, then when distance A (speaker A to the point) = distance B -+ n Lambda
n= 0, 1, 2, ... constructive interference occurs. The easy solution is in the center, n=0. I suspect you will find a +- 1 solution.