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Homework Help: Error propagation for effective spring constant

  1. Oct 11, 2012 #1
    1. The problem statement, all variables and given/known data

    Calculate the error propagation for the theoretical effective spring constant for the two springs. The actual values don't matter, it's just supposed to show how it would be calculated.

    2. Relevant equations

    ke=k1*k2/(k1+k2)

    3. The attempt at a solution

    ke=A*B/(A+B) (Let A=k1, B=k2)

    I have come up with two possibilities, but I'm not sure if either is correct. The addition in the denominator is confusing me.

    Possibility 1: σ(ke)/|ke|=σ(A)/|A| + σ(B)/|B| + σ(A) +σ(B)


    Possibility 2: σ(ke)/|ke|=σ(A)/|A| + σ(B)/|B| + (σ(A) +σ(B))/|A+B|
     
  2. jcsd
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