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Carlos runs with a velocity

  1. Sep 23, 2009 #1
    1. The problem statement, all variables and given/known data
    Carlos runs with a velocity of = (6 m/s, 25° north of east) for 10 minutes. How far to the north of his starting position does Carlos end up?

    2. Relevant equations



    3. The attempt at a solution

    I thought maybe you would solve this problem like you do for x and y components? if so...where does the 10 min. go?
     
  2. jcsd
  3. Sep 23, 2009 #2

    kuruman

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    You do have to solve considering x and y components. The time goes in the relevant kinematics equations of motion. What are they?
     
  4. Sep 23, 2009 #3
    V = Vo + at
    X - Xo = Vot + .5at2
    v2 = vo2 + 2a(X - Xo)
    X - Xo = .5(Vo + V)t
     
  5. Sep 23, 2009 #4

    kuruman

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    There is also a similar set of equations for the y direction. What should you use for the acceleration in the x and y direction?
     
  6. Sep 23, 2009 #5
    i have no clue...i am confused
     
  7. Sep 23, 2009 #6

    kuruman

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    Read the problem. Draw North-South and East-West axes. Can you picture in your mind how Carlos is moving? Reread the problem. Is the Carlos' sped increasing, decreasing or staying the same? Does his direction of motion change?
     
  8. Sep 23, 2009 #7
    I think his speed is staying the same... doesn't his direction stay the same as well
     
  9. Sep 24, 2009 #8

    kuruman

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    Yes, his speed and direction stay the same. This means that his velocity does not change. If his velocity does not change, what can you say about his acceleration?
     
  10. Sep 24, 2009 #9
    acceleration is zero
     
  11. Sep 24, 2009 #10

    kuruman

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    Very good. Now put zero in the place of acceleration a in the kinematic equations and write one set for the x-direction and a second set for the y-direction.
     
  12. Sep 24, 2009 #11
    which equation do I use? is there a way you could show me the first step?
     
  13. Sep 24, 2009 #12

    kuruman

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    V = Vo + at becomes V = Vo + 0*t becomes V = Vo.

    Now that you know that V = Vo, replace V in the other three equations and replace a with zero like I did above.

    X - Xo = Vot + .5at2
    v2 = vo2 + 2a(X - Xo)
    X - Xo = .5(Vo + V)t

    Then repeat with y replacing x everywhere.
     
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