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Homework Help: DE: Resistant force, 2 equations

  1. Oct 6, 2008 #1
    So I'm given two equations, but not really told when it's appropriate to use one over the other.

    1) The resistance is proportional to the velocity

    [tex]F=-mg-rv[/tex]

    2) The magnitude of the resistance is proportional to the square of the velocity

    "the magnitude" ... what's the difference?

    [tex]F=-mg-k|v|v[/tex]
     
  2. jcsd
  3. Oct 7, 2008 #2

    gabbagabbahey

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    Are some of these quantities suppose to be vectors?
     
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