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Average velocity backpacker

  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 1.33 m/s, due west. This average velocity results because she hikes for 6.44 km with an average velocity of 2.60 m/s, due west, turns around, and hikes with an average velocity of 0.425 m/s, due east. How far east did she walk?

    2. Relevant equations



    3. The attempt at a solution

    average V= delta r/delta t. since i dont know the time i found that first using v= d/t. 2.6= 6.44/t. t=2.48. using that i set up the equation saying 1.33= 2.6-0.425/2.48-t_0 and solved for t_0 which got me 0.844 and since we are looking for a distance i said v= d/t so 0.425= d/0.844= 0.3587 km....but its wrong
     
  2. jcsd
  3. Sep 9, 2009 #2

    rl.bhat

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    If d is the distance traveled due east, time taken will be d/0.425 = 2.35*d s.
    The average velocity 1.33 = (6440 - d)/(6440/2.6 + 2.35*d)
    Now solve for d.
     
    Last edited: Sep 9, 2009
  4. Sep 9, 2009 #3
    d/0.425 = 2.35*d
    it will give me d/d = 5.53 which i dont understand and where does the 2.35 come from?
     
  5. Sep 9, 2009 #4

    rl.bhat

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    it will give me d/d = 5.53
    How did you get this one?
     
  6. Sep 9, 2009 #5
    sorry i wrote the wrong number. well you gave me the equation d/0.425 = 2.35*d so 2.35d*0.425=d : d=0.99875d. so d/d=099875 ??
     
  7. Sep 9, 2009 #6

    rl.bhat

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    No. It is not correct.
    Go through #2. again. I have done sum editing.
    Solve for d.
     
  8. Sep 9, 2009 #7
    is this suppose to be a fraction over a fraction?
     
  9. Sep 9, 2009 #8

    rl.bhat

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    No. It is
    1.33 = (6440 - d)/(2477 + 2.35d)
     
    Last edited: Sep 9, 2009
  10. Sep 11, 2009 #9
    so
    1.33*(2477+2.35d)= 6440-d
    3294.41+3.126d= 6440-d
    -3145.59+3.126d= -d
    ? what do i do from there?
     
  11. Sep 11, 2009 #10

    rl.bhat

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    3145.59 = 3.126d + d
     
  12. Sep 11, 2009 #11
    ok so if i add 3.126d+d then that gives me 4.126d
    so 3145.59= 4.126d
    3145.59/4.126=d
    d= 762.94
    but thats wrong...???
     
  13. Sep 11, 2009 #12

    rl.bhat

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    1.33 = (6440 - d)/(2477 + 2.35d)

    Rewrite this step.
    1.33 = (6440 - d)/(2462 + 2.353d)
    Now calculate.
     
  14. Sep 12, 2009 #13
    1.33*(2462+2.353d)= 6440-d
    3274.46+3.129d= 6440-d
    -3165.54+3.129d= -d
    3165.54= d+ 3.129d
    3165.54= 4.129d
    d= 766.7
    but thats wrong....
     
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