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Homework Help: I need confirmation please

  1. Jun 12, 2007 #1
    The driver of a truck slams on the brakes when he sees a tree blocking the road. The truck slows down uniformly with an acceleration of -5.60 m/s2 for 4.20 s, making skid marks 62.4 m long that end at the tree. With what speed does the truck then strike the tree?

    equation: dx = vot + .5at^2
    62.4 m = v (4.20s) + .5 (-5.60 m/s^2) (4.20s)
    v=26.6 m/s

    May you experts please check if this is correct? Thanks a bunch.
  2. jcsd
  3. Jun 12, 2007 #2


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    is vot the initial velocity*time ?

    if so is the case, you only calculated the initial speed of the truck.

    v=vo + at
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