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Homework Help: Simple Constant acceleration equation but I dont get it!

  1. Apr 4, 2010 #1
    1. The problem statement, all variables and given/known data

    A particle moving at 5 m/s reverses its direction in 1s to move at 5 m/s in the opposite direction. If is acceleration is constant, what distance does it travel?


    2. Relevant equations
    The constant acceleration equations

    3. The attempt at a solution
    I use x=vot + 1/2at2 were a= (vfinal- vinitial)/t. I get the wrong answer. Something about having to plug in half the time for some reason that I don't understand. Would some one please help me out?
     
  2. jcsd
  3. Apr 4, 2010 #2

    kuruman

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    Can you show us what answer you got and how?
     
  4. Apr 4, 2010 #3
    I get get the answer to be distance equals 0 because i use:

    vi to be 5 m/s
    vf to be -5m/s
    a to be -10

    I plug those in to the equations mentioned above. It seems to be the incorrect answer but doesn't it make sense? I must be missing fundamental here.
     
  5. Apr 4, 2010 #4

    kuruman

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    You have correctly found zero which is the displacement. However the problem is asking to find the distance. Distance is not the same as displacement. Imagine an odometer hooked up to the particle. By how much has the odometer changed when the particle has gone out and come back to where it started?
     
  6. Apr 4, 2010 #5
    I got it. Thanks.

    Much much karma to you.
     
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