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Homework Help: Hooke's Law: Two springs in series

  1. Dec 20, 2007 #1
    [SOLVED] Hooke's Law: Two springs in series

    can someone explain and prove to me why the equation for two springs in series is
    K= [(1/k1)+(1/k2)]^-1 ?


    this is how far i got
    F= -k ∆x
    F= -k (x1+x2)
     
  2. jcsd
  3. Dec 20, 2007 #2

    rock.freak667

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    Homework Helper

  4. Dec 20, 2007 #3
    thanks
    i looked at it but i dont understand this part

    "Meanwhile, the force on the point between the two springs is
    Fs = -k1x1+k2(x2-x1)"
     
  5. Dec 20, 2007 #4

    Doc Al

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    Staff: Mentor

    The proof on that website is rather obscure. Instead, try this: What's the force exerted by each spring and by both springs?

    F = k1x1 = k2x2 = k(x1 + x2)

    Play around with this and you should be able to figure out k in terms of k1 and k2.
     
  6. Dec 20, 2007 #5
    thanks doc al
    this might be a stupid question
    but k1x1 = k2x2 is it because the tension of both spring are equal?
     
  7. Dec 20, 2007 #6

    rock.freak667

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    Homework Helper

    Because the force is the same,yes
     
  8. Dec 20, 2007 #7
    kk i think i got it
    thanks for helping me =]
     
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