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Struggling to understand how I get this answer

  1. Mar 11, 2016 #1
    Struggling to understand how this answer works.
    This is just a worked example from a university paper.

    W = 220∫ V^-1 dV.....between the limits of 0.1 & 0.2....(Answer is 152.49 Rad)

    I understand that the basic rule for a negative power would give us ln x, but from here I would say that the answer would be the difference of ln 0.2 and ln 0.1?
    I need to get ln(2) for the answer to be correct, just not sure how?
     
  2. jcsd
  3. Mar 11, 2016 #2

    Merlin3189

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    Surely ln(0.2) - ln(0.1) = ln(0.2/0.1) = ln(2)
     
  4. Mar 11, 2016 #3
    I was deducting ln 0.1 from ln 0.2, thanks
     
  5. Mar 12, 2016 #4

    SteamKing

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    Same difference:

    ln (0.2) = -1.6094
    ln (0.1) = -2.3026

    ln (0.2) - ln (0.1) = -1.6094 - (-2.3026) = 0.6931 = ln (2)
     
  6. Mar 13, 2016 #5
    Ah. I see. That makes it clearer. Thanks
     
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