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Retarding force acting on a particle

  1. Sep 28, 2009 #1
    1. The problem statement, all variables and given/known data
    A particle of mass m moving along a straight line is acted on by a retarding force F=be^(av) where b and a are constants and v is the velocity. At t=0 it is moving with velocity v(0) . Find the velocity at later times.


    2. Relevant equations
    F=ma=m(dv/dt)


    3. The attempt at a solution
    I tried taking the integral of the force equation to solve for v from dv/dt but I'm not sure where to go from there. The answer in the book is v(t)=(1/a)ln(1/(abt/m+e^(-av))
     
  2. jcsd
  3. Sep 28, 2009 #2

    rl.bhat

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    Homework Helper

    Hi vballgurl154, welcome to PF.
    Unless we see your calculations, we are not able to point out your mistakes.
    Now F = dv/dt = b*e^(av)
    So dv/(b*e^av) = dt.
    So 1/b*Intg(e^-av) = Intg(dt) + C
    Find the value of C by applying the initial conditions.
     
  4. Sep 30, 2009 #3
    thank you!!! i figured it out :)
     
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