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Homework Help: Hooke's law problem

  1. Apr 18, 2010 #1
    1. The problem statement, all variables and given/known data

    In a pole with dimension lo=5m and section S=20 cm square acts the force of F=20Kn vertically
    downwards . How long will it go downwards, ---- thus delta l is needed
    2. Relevant equations

    I have delta l /lo =1/ EY *F/S

    3. The attempt at a solution

    I know the solution is giving me only delta l = 0.25 mm

    how do i get delta l from above formula and what about EY which isnt needed ?

    Could this be correct delta l = lo/ey * F/s ?
  2. jcsd
  3. Apr 18, 2010 #2


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    Does the force act along the "direction of the pole"? And aren't you given any value for E?
  4. Apr 18, 2010 #3
    Yes it does . Like its written in the book I see E is not given any number ! thats yungs module btw.
  5. Apr 18, 2010 #4


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    If this is the correct statement of the problem, then I don't see how to calculate the elongation without Young's modulus.
  6. Apr 18, 2010 #5
    Your correct thanks for help
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