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Quadratic formula problem

  1. Apr 11, 2007 #1

    ssb

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    1. The problem statement, all variables and given/known data

    A physics student with too much free time drops a watermelon from the roof of a building height H. He hears the sound of the watermelon going "splat" after a time interval of Delta T.
    You may ignore air resistance. How high is the building? The speed of sound is Vs.

    2. Relevant equations

    Quadratic formula
    physics

    3. The attempt at a solution

    Ok T = T1 +T2 = H/Vs + sqrt(2H/g)

    (T - H/Vs)^2 = 2H/g

    Therefore

    T^2 - (2TH/Vs) + (H/Vs)^2 - 2H/g = 0

    I want to solve for H.
    How do I plug this into the quadratic formula so that I can solve for H? Im only used to there being 3 terms in the poly nomial (like x^2 + x + 4). Im thinking I have to combine the -(2TH/Vs) and -2H/g somehow but I dont know how!!!!! Please help!
     
  2. jcsd
  3. Apr 11, 2007 #2

    hage567

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    Homework Helper

    Yes, you combine the two terms, and take out the H. That will leave you with three terms in the form of a quadratic equation.
     
  4. Apr 11, 2007 #3

    ssb

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    Ok I combined them and got H (-2t/Vs - 2/g)

    So tell me if this is correct

    a = 1/Vs

    b = (-2t/Vs - 2/g)

    c = t^2

    Because when I plug that in as an answer it comes back wrong.
     
  5. Apr 11, 2007 #4

    hage567

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    Homework Helper

    One thing I see is that a should be 1/Vs^2.
     
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