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Homework Help: Finding the acceleration vector component

  1. Mar 2, 2012 #1
    1. The problem statement, all variables and given/known data

    A ball travels vertically upward with quadratic air resistance, find the acceleration component.

    2. Relevant equations

    So, I have x pointing vertically downward and

    C=0.20 D = Diameter V=velocity

    W= -mgi
    R = -C^2D^2V^2


    ma= -mg-C^2D^2V^2

    3. The attempt at a solution

    a(t)= dv/dt

    dv/dt = (-mg-C^2D^2V^2)/m

    After doing the integration it seems not to make any sense. Any help where I have gone wrong? Am I along the right lines?
  2. jcsd
  3. Mar 2, 2012 #2


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    Science Advisor

    Well, why are you integrating? The problem, according to you, asks for the acceleration, not the velocity.
  4. Mar 3, 2012 #3
    OK, I think that just got me the equation for the acceleration of a resisted projectile

    r(t)= -g - (c*D^2*v/m)

    So, differentiating this twice should give the acceleration componet? I know the answer I should get and it does not match. Any help?
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