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Homework Help: Problems for Understanding

  1. Sep 16, 2009 #1
    1. The problem statement, all variables and given/known data

    A cyclist is traveling with an average velocity of 5.9 m/s[W]. What will be his displacement after 1.2 h?

    2. Relevant equations

    d = v1▲t+½a▲t^2 ?

    3. The attempt at a solution

    Vavg = 5.9 m/s
    ▲t = 1.2 x 60 = 72 m/s

    What I did was use d = v x t and I got 424m/s, which is 1, 526.4 km/h. But that's way off from my the textbook's answer which is, 26km[W]..

    It sounds so easy but honestly, I'm going crazy trying to figure it out LOL :redface:.
  2. jcsd
  3. Sep 16, 2009 #2


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    Homework Helper

    Cyclist is traveling with uniform velocity.
    So the displacement = velocity*time.
    Convert 1.2 hours to seconds
  4. Sep 16, 2009 #3
    You gotta get everything in the same units. We have velocity in m/s so we want time in seconds.

    1.2 hours = 72 minutes = 4320 seconds

    Then just use:

    Distance = Velocity*Time
  5. Sep 16, 2009 #4
    Thanks guys.
    So I did D = 5.9m/s x 4320 which equaled to 25, 488m/s?
    Then, to change it back to km/h, times 3.6 then it equaled 91, 756.8?!
    What am I doing wrong? :(
  6. Sep 16, 2009 #5


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    In the problem displacement is asked, not the velocity.
  7. Sep 17, 2009 #6
    Hm, right.. AMG, I still don't get this :'(
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