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Homework Help: 1-D Motion Problem

  1. Feb 8, 2006 #1
    A truck covers 40.0 m in 8.50 s while smoothly slowing down to a final speed of 2.80 m/s. (a) Find the truck's original speed. (b) Find it's acceleration.

    I used the 2nd formula originally (X=VoT+1/2aT^2) but I wasn't getting anywhere. Can someone point me in the right direction on how to do this problem? Any help is appreciated. Thanks.
     
  2. jcsd
  3. Feb 8, 2006 #2

    Doc Al

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    Try figuring out the average speed of the truck and see what that tells you.
     
  4. Feb 8, 2006 #3
    I found it to be 4.71 m/s but I'm still stuck. Where do I go next?
     
  5. Feb 8, 2006 #4

    Doc Al

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    Good. Now use that to find the initial speed:
    [tex]v_{ave} = (v_i + v_f)/2[/tex]
     
  6. Feb 8, 2006 #5
    Thanks for your help. I really appreciate it.

    I got 6.62 m/s for part A and used V=Vo+at to get -.45m/s^2 on part B.

    I hope this is correct. I'm pretty sure A is.

    Can anyone confirm?
     
    Last edited: Feb 8, 2006
  7. Feb 9, 2006 #6

    Doc Al

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    Looks good to me.
     
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