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Homework Help: Mechanics prove 2

  1. Jun 3, 2010 #1
    1. The problem statement, all variables and given/known data

    A particle with mass m is projected vertically upwards from a point with speed u. THe particle, besides being subjected to gravity, experiences a resistive force of magnitude
    mkv^2, with v as its velocity when its height from the point of projection is x and k as a positive constant. Show that

    [tex]v^2=(\frac{g}{k}+u^2)e^{-2kx}-\frac{g}{k}[/tex]

    2. Relevant equations



    3. The attempt at a solution

    F-mkv-mg=ma

    using v^2=u^2+2as

    v^2=u^2-2gx

    thats all i can get
     
  2. jcsd
  3. Jun 3, 2010 #2
    Did you know that the equation v^2 = u^2 + 2as only holds for constant acceleration? You will have to integrate in this case due to the varying acceleration.
     
  4. Jun 3, 2010 #3
    thanks , for this , do i integrate

    F-mkv-mg=ma ?

    am i supposed to get rid of some of the terms here first before i integrate ?
     
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