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Physics boulder problem

  1. Aug 26, 2011 #1
    1. The problem statement, all variables and given/known data
    An alert hiker sees a boulder fall from a cliff. He notes that it takes 1.3 sec for the boulder to travel the last third of the fall. a.)Find the height H of the cliff. B.) If you found a quadratic equation of two solutions for a.) what is the relevance of the other one
    2. Relevant equations
    v2=vo2+2gX
    X=vot+0.5gt2
    3. The attempt at a solution
    v2=vo2+2gX ;vo=0;X=H/3
    v2=2(9.8m/s2)(H/3)
    v=sqrt(13.07m/s2H)

    X=vot+0.5gt2
    H/3=sqrt(13.07m/s2H)(1.3s)+8.281m
    H=3.9ssqrt(13.07m/s2H)+8.281m
    H-3.9ssqrt(13.07m/s2H)-8.281m=0
    I just used my calculator to solve this quadratic equation
    sqrt(H1)=14.66m0.5
    H=214.9 which is the same with the book's answer
    sqrt(H2)=-0.56m0.5
    H2=0.3136m
    I cant answer B.) What is the relevance of H2
    Please reply,, Thanks!!
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Aug 26, 2011 #2

    PeterO

    User Avatar
    Homework Helper


    Firstly, were your answer(s) to the first part correct - I don't want to spend time proving you are correct/incorrect.
     
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