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One-Dimensional Motion With Constant Acceleration

  1. Sep 11, 2009 #1
    A truck covers 40.0 m in 8.50 s while smoothly slowing down to a final velocity of 2.80 m/s

    a. Find the truck's original speed.

    b. Find its acceleration


    a) I'm using x=1/2(vo+v)t to find the original velocity but I keep getting vo=12.21m/s (the books answer is 6.61m/s)

    b) For the second part to find acceleration I'm using v=vo+at which gives me a=-1.1m/s^2 (the books answer is -0.448m/s^2)

    I don't know what I'm doing wrong
     
  2. jcsd
  3. Sep 11, 2009 #2

    rl.bhat

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    [I'm using x=1/2(vo+v)t to find the original velocity but I keep getting vo=12.21m/s (the books answer is 6.61m/s)]

    Show this calculation.
     
  4. Sep 11, 2009 #3
    40=1/2(vo+2.8)8.5

    40(2)/8.5=vo+2.8

    9.41=vo+2.8

    Ahhh I see now, I had a minus sign in there before. I'm getting the right answer now.

    vo=6.61m/s

    Thanks so much for the response, you've helped me avoid a total meltdown. Seriously, I appreciate it.
     
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