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Homework Help: Work Problem

  1. Jul 9, 2009 #1
    1. The problem statement, all variables and given/known data
    You have a 4kg block attached to a string with T=35N. If the block begins at 5m/s and is lowered 10m what is approxaimate final velocity of block?

    So I got the question right:
    Find Fnet and times it by 10m and set (Fnet)(10)= work = KE and find velocity from KE.

    But my question is W= PE + KE so where is the PE?

    Thanks for the help.
  2. jcsd
  3. Jul 9, 2009 #2


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  4. Jul 9, 2009 #3


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    The net work done by all forces is the change in KE
    The work done by non-conservarive forces is the change in (KE +PE). You should carefully note the differences between the 2 equations. The latter incorporates the work done by gravity or other conservative forces in the PE term.
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