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Homework Help: Delta sign confusion

  1. Oct 2, 2007 #1
    1. The problem statement, all variables and given/known data
    Hans stands at the of the Grand Canyon and yodels down to the bottom. He hears his yodel echo back from the canyon floor 5.20s later. Assume that the speed of sound in air is 340.0m/s. How deep is the canyon at this location?

    I made a chart.
    Velocity Original = 340
    Velocity Final= Unknown
    Distance= x
    Gravity = 9.81
    Time = 5.20

    The equation I'm using is

    I pretty much do the equation, I just need to know what I need to do for delta. (divide, mulitply, etc. I'm in Physics PRE-AP, Algebra, 9th grade. Advanced classes, blah.)

    2. Relevant equations
    Not sure what you mean?

    3. The attempt at a solution
    I plugged in the numbers:
    vf= 340 + 9.81 (DELTA) 5.20

    For delta, I used division. (VF-VO/G = T?)
    I plugged in the numbers:
    I got -34.65
    This is probably wrong... >_<
  2. jcsd
  3. Oct 2, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    The equation you need is simply [itex] s=\frac{d}{t} [itex]. Sound is a pressure wave and doesn't behave like a kinematic particle. Its speed is essentially constant.
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