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Help with Kinematics problem

  1. Aug 13, 2012 #1
    1. The problem statement, all variables and given/known data
    You nose out another runner to win the 100.000 m dash. If your total time for the race was 11.800 s and you aced out the other runner by .001 s, by how many meters did you win?



    2. Relevant equations
    vavg=Δx/Δt
    v=x/t

    3. The attempt at a solution
    I have the answer already with the method for solving it:
    v=x/t = 100.00m/11.8s =8.4746m/s.
    v=x/t = x=vt = 8.4746m/s(.001s)= .008m

    This is the provided answer, however, I tried a different method and got ".0008m" instead, I don't know why. Here's what I did

    100m/11.8s= 8.474576271 m/s (this is the average velocity of the winner)
    100m/11.8001=8.474504453m/s (this is the average velocity of the loser)

    I multiplied the avg velocity of the loser by 11.8, to get the position of the loser as the winner wins.
    I got 99.99915255 m. I subtracted this from 100, to see by how many meters the winner won by and I got
    .00084745 meters. Don't know why I got an extra 0 in my answer, can anyone please explain? Thanks!
     
  2. jcsd
  3. Aug 13, 2012 #2

    PeterO

    User Avatar
    Homework Helper

    The two values in red do not match. Second should be 11.801
     
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