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Homework Help: Kinematic Equations Used to Find A.) Average Speed & B.)Acceleration

  1. Sep 17, 2014 #1
    1. The problem statement, all variables and given/known data

    A truck covers 40.0m in 7.15 s while uniformly slowing down to a final velocity of 3.50 m/s. a.) Find the truck's original speed b.) Find it's acceleration

    2. Relevant equations

    Δx = Vav(Δt) = (V+Vo/2)Δt


    3. The attempt at a solution

    Part A.)

    1.) I used the formula Δx = Vav(Δt) = (V+Vo/2)Δt

    2.) Plugged in what is given & solved for Vo


    Vo=12.5 m/s

    Part B.)

    1.) I used the formula a=(V-Vo)/(Δt)

    2.)Plugged in what I have

    (3.50 m/s-12.5 m/s)/(7.15s) = -1.26 m/s2

    Apparently both my answers are wrong and I am not sure what I am doing wrong. I tried this multiple times, as well as other different versions of this problem which I get correctly.

    Your input would be appreciated. Thanks :)
  2. jcsd
  3. Sep 17, 2014 #2


    User Avatar
    Science Advisor

    Check your algebra here.

    It will be correct when you fix your Vo. :smile:
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