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Stretching distance of spring

  1. Jan 13, 2013 #1
    1. The problem statement, all variables and given/known data
    See image attachment

    2. Relevant equations
    Fs = kx
    Es = 1/2 kx^2
    ET1 = ET2 which is Eg1 + Ek1 + Es1 + work applied = Eg2 + Ek2 + Es2 + friction

    3. The attempt at a solution
    grade 12. Please help i never did anything like this.
     

    Attached Files:

  2. jcsd
  3. Jan 13, 2013 #2

    Doc Al

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    Staff: Mentor

    This is a force/equilibrium problem, not an energy problem.

    A hint to start you off: If you look at diagram I and imagine the spring cut into three pieces, how much does each piece stretch?
     
  4. Jan 13, 2013 #3
    each piece will stretch 1 cm
     
  5. Jan 13, 2013 #4

    Doc Al

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    Staff: Mentor

    Good. So now you know that the weight of the complete rod will stretch one of the spring pieces by 1 cm. How much will the weight of 1/3 of the rod stretch one of those spring pieces?

    Use this reasoning to figure out how much each spring stretches in diagram II.
     
  6. Jan 13, 2013 #5
    1/3 x 1cm = 1/3cm
    is it 1/3cm + 2/3cm + 3/3cm = 2cm
     
  7. Jan 13, 2013 #6

    Doc Al

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    Staff: Mentor

    Good!
     
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