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Easy velocity/acceleration problem, could use some help please

  1. Sep 9, 2009 #1
    1. The problem statement, all variables and given/known data

    In reaching her destination, a backpacker walks with an average velocity of 1.21 m/s, due west. This average velocity results because she hikes for 6.44 km with an average velocity of 2.54 m/s, due west, turns around, and hikes with an average velocity of 0.470 m/s, due east. How far east did she walk?

    2. Relevant equations

    V = Xf - Xo
    T


    3. The attempt at a solution
    From what I understand the time it takes to go west 6440 plus the time it takes to go east = the total time it takes to go the full distance. I believe you set it up like

    6440-X2 6440 X2
    _____ = _____ + _____

    0.470 2.54 0.470


    I'm not sure if this is wrong or my arithmetic is just failing me. Any help would be great.

    Thanks
     
  2. jcsd
  3. Sep 9, 2009 #2

    rl.bhat

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    See the triple777's post.
     
  4. Sep 9, 2009 #3
    I was just looking it over but I do not understand where you pulled 2.35 from
     
  5. Sep 9, 2009 #4

    rl.bhat

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    It is 1/0.425
     
  6. Sep 9, 2009 #5
    Ok I dont really see why you do that, but I can figure it out hopefully. At the end you write the equation once as The average velocity 1.33 = (6440 - d)/(6440/2.6 + 2.35*d)
    then at the end you said 1.33 = (6440 - d)/(2477 - 2.35d)

    Is there some reason the signs are switched before the 2.35d? I'm not really sure how to do the algebra at the end either with moving it around if any help could come there.
    I have something like 1.21 = (6440 - d)/(2535.43 + or minus i dunno 2.13d).
     
  7. Sep 9, 2009 #6

    rl.bhat

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    It should be +2.35*d. If it is -ve it is typo.
     
  8. Sep 9, 2009 #7
    I really can't seem to get the right answer if you wouldnt mind helping further. I seem to be coming up with 2143.35m, but that does not seem to be the answer.
     
  9. Sep 9, 2009 #8
    I got it now thank you very much for your help.
     
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