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Homework Help: I need physics help bad please help

  1. Jan 24, 2005 #1
    A truck covers 40.0 m in 7.65 s while smoothly slowing down to final speed 3.40 m/s. whats the original speed and what is its acceleration?? The initail position is 0, the final position is 40. THe initial velocity we don't know, the final velocity is 3.40 m/s. The time it takes is 7.65 and the acceleration we don't know. Do I have that right? and when I set it up in the formulas there are two unknowns and I work it out and it never comes out to be the right answer.
    Last edited: Jan 24, 2005
  2. jcsd
  3. Jan 24, 2005 #2


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    Homework Helper

    Are you familiar with :

    [tex]s = vt - \frac{1}{2}at^2[/tex]

    and [tex]v = u + at[/tex] ?

    use the 1st to solve for a (you're given the rest), then use that value of a to find u with the second equation.
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