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Homework Help: Final speed

  1. Sep 21, 2007 #1
    1. The problem statement, all variables and given/known data

    driver slams breaks. car slows with acceleration of -5.6m/s^2 for 4.20s for 62.4m.

    2. Relevant equations

    with wat speed does the car then strike an object?

    3. The attempt at a solution

    i thought of using equation Xf=Xi+Vi(t)+1/2at^2
    i am not sure if this is the best choice but when using this i am getting stuck with the initial velocity. am i in the right track
  2. jcsd
  3. Sep 21, 2007 #2


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    Homework Helper

    Yes, you can use that equation. Find vi, then you can find vf...
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