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Finding an Equation through Integrals

  1. Feb 1, 2010 #1
    Position Function from Constant Acceleration Equation

    1. The problem statement, all variables and given/known data

    The acceleration of a certain rocket is given by ax = bt, where b is a positive constant.

    (a) Find the position function x(t) if x = x0 and v0 at t = 0. (Use x_0 for x0, v_0 for v0, b, and t as necessary.)
    x(t) =


    2. Relevant equations

    (Hint given): The velocity function is the time integral of the acceleration function. The position function is the time integral of the velocity function. The two integration constants can be determined by applying the given initial conditions when the time is equal to zero.

    [tex]\Delta[/tex]s = vi([tex]\Delta[/tex]) + (1/2)a([tex]\Delta[/tex])2


    3. The attempt at a solution

    ax = bt

    so a = bt

    v = int (a dt) = b * int (t dt) = b (.5t2)

    x = b/2 int (t2) dt

    Is my thinking in the right spot? I don't know if I'm not integrating correctly or if I need to plug the integrations into an equation...?
     
    Last edited: Feb 1, 2010
  2. jcsd
  3. Feb 1, 2010 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    You have to include a constant C when integrating. So v=0.5*b*t2+C.

    If the initial velocity is v0, C=v0.

    Now integrate v(t), do not forget the integration constant again.

    ehild
     
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