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Homework Help: Sound Question

  1. Feb 28, 2005 #1
    Need some help with this question. I think I know how to do it but I dont know the speed of sound. Could someone let me know what it is?

    A rifle is fired in a valley with parallel vertical walls. The echo from one wall is heard 6.0 s after the rifle was fired. The echo from the other wall is heard 6.0 s after the first echo. How wide is the valley?
  2. jcsd
  3. Feb 28, 2005 #2
    The generally used value for the speed of sound is 1100ft/s. In reality, the actual value is dependant on barometric pressure, altitude and temperature. Interestingly, 1100 ft/s has become common in textbooks because of an idealized calculation of the speed of sound in introductory fluid dynamics. The calculation is actually wrong, it ignores the pressure effect of compressive heating. But for your problem 1100ft/s will do fine.
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