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Homework Help: Goldstein classical mechanics discrepancy?

  1. Sep 18, 2012 #1
    1. The problem statement, all variables and given/known data

    In Goldstein's text, he discusses conservative fields and then states that "friction or dissipative forces are never conservative since F dot ds is always positive."

    From what I recall, most frictional interactions occur in directions opposite the displacement, and would, hence, result in negative values of the dot product. Shouldn't, then, the text read isntead: friction or dissipative forces are never conservative since F dot ds is always non-zero?

    I have checked a few other classical mechanics texts and they all seem to have statements along the same lines- so I feel there is a detail I am missing here.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 18, 2012 #2


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    I still have my 1st edition of Goldstein that I used in a course 42 years ago. I found the quote on page 3 and lo and behold I see that I had circled the word "positive" and added a question mark in the margin! I think Goldstein meant to use the word "negative" here (even though you can construct scenarios where a force of friction does positive work).
  4. Sep 18, 2012 #3
    That's remarkable TSny, thanks for checking!
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