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Mistake in solving for work in physics?

  1. Apr 7, 2008 #1
    1. The problem statement, all variables and given/known data
    a student wearing a frictionless in-line skates on a horizontal surface is pushed by a friend with a constant force of 45N. How far must the student be pushed, starting from rest, so that her final kinetic energy is 352J?

    2. Relevant equations

    3. The attempt at a solution
    Vf=12.39 and Vi=0 since it starts from rest



    I just wanted to know if that was a correct way of solving it or did i make a mistake somewhere?
    thx for the help.
  2. jcsd
  3. Apr 7, 2008 #2

    Doc Al

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    Staff: Mentor

    Since you are given the final KE, these calculations are not needed. (Note how error creeps in: 352.31 should really be 352.)

    This is all you need. (Use the given value for KE.)
  4. Apr 7, 2008 #3
    the Wnet is always the same as KE?
  5. Apr 7, 2008 #4

    Doc Al

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    Staff: Mentor

    The net work will equal the change in KE. That's the so-called Work-KE theorem.
  6. Apr 7, 2008 #5
    ooo thxx hehe
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