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Terminal speed with linear drag

  1. Sep 24, 2014 #1
    1. The problem statement, all variables and given/known data
    An object moves through a liquid horizontally against a linear drag force given by F = -cv
    What is the terminal velocity? Initial Velocity is V_0


    2. Relevant equations
    F=ma


    3. The attempt at a solution

    m(dv/dt) = -cv
    -->
    (dv/v) = (-c/m)dt
    ln(vf/v0) = -ct/m
    vf=v0*e^(-ct/m)

    which says that as time goes to infinity that vf will equal v0 but that doesn't make any sense physically... what did I do wrong here?
     
  2. jcsd
  3. Sep 24, 2014 #2

    vela

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    Take the limit incorrectly? ##V_f## approaches 0 as ##t \to \infty##, no?
     
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