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Grade 11 U Kinematics

  1. Oct 13, 2009 #1
    Hey, guys just joined PF, was hoping you could help with this questions and in turn maybe i can return the favour (with the little physics knowledge I have).

    1. The problem statement, all variables and given/known data
    In a acceleration test, 2 markers are placed 0.30 km apart. The first car passed the first marked with a velocity of 5.0 m/s [E], the second passed the marker with a velocity of 33.0 m/s [E]. Calculate the Cars average acceleration.

    2. Relevant equations
    v1 = 5.0 m/s [E]
    v2 = 33 m/s [E]
    Delta D = 0.30 km
    Aav = ?

    The kinematics that i am using is Vf² = Vi² + 2aav(d)
    3. The attempt at a solution
    The problem i am having is rewriting the equation.
    I need to rewrite this for aav.

    Vf² - Vi² = Vi² + 2aav(d)

    vf² - vi²/2(d) = aav

    This is what i have so far, but it must be wrong i just dont see how. When i plug in the numbers..

    1089 - 25/2(0.3) = aav
    1064/0.6 = aav
    aav = 1773.3

    this cant be right can anyone help me?
  2. jcsd
  3. Oct 13, 2009 #2


    User Avatar
    Homework Helper

    Hi CraZyFanAtic, welcome to PF.
    Convert the distance from kilometer to meter.
  4. Oct 13, 2009 #3
    O, wow do i feel stupid. First time ive seen a question like that just didn't think about it, thanks alot. Saved me alot of time.
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