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Projectile Question Need help fast

  1. Sep 22, 2009 #1
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 22, 2009 #2

    rock.freak667

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    42??
     
  4. Sep 22, 2009 #3
    srry there is the question A pilot is required to fly directly from London, UK, to Rome, Italy in 3.5 h. The displacement is 1.4 x 10^3 hm [43 degrees E of S]. A wind is blowing with a velocity of 75 km/h [E]. Determine the required velocity of the plane relative to the air.
     
  5. Sep 22, 2009 #4

    rock.freak667

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    ok then, how fast should the plane fly if the wind was not blowing?

    Now use this vector addition

    [tex]\vec{V_{P/A}}= \vec{V_P} - \vec{V_A}[/tex]
     
  6. Sep 22, 2009 #5
    srry for the late reply im kinda new at this... it would be 1325?
     
  7. Sep 22, 2009 #6

    rock.freak667

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    I don't think that is the answer.

    If the plane must travel 1.4x103 km in 3.5h , how fast should it travel? (this is vp)

    When you get this vp acts 43 degrees E of S, so on your vector diagram draw this and vA=75 km/h E.
     
    Last edited: Sep 22, 2009
  8. Sep 22, 2009 #7
    ^
    |43
    |
    |
    1400 |________> looks right?
     
  9. Sep 22, 2009 #8
    ^
    |
    |
    |
    |________> looks right? the left side is 1400 km, top left is 43 degrees, bottom is 75
     
  10. Sep 22, 2009 #9
    o wait is the hypotnuse 1400 instead?
     
  11. Sep 22, 2009 #10

    rock.freak667

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    Code (Text):
    ------------
    \ 43
     \
      \
       \
    should be like this 43 degrees south of east.

    Draw the velocity of air now. And then find


    [tex]\vec{v_{P/A}} = \vec{v_P} - \vec{v_A} =\vec{v_P} + (- \vec{v_A})[/tex]

    EDIT: you need to find vP and draw this on the diagram with the air. You can't have a vector diagram adding different types of vectors
     
  12. Sep 22, 2009 #11
  13. Sep 22, 2009 #12

    rock.freak667

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    what units are that in? Put vP in km/h
     
  14. Sep 22, 2009 #13
    ok 1325 km/h
     
  15. Sep 22, 2009 #14
    wat does the time have to do with this question now?
    to find distance?
     
  16. Sep 22, 2009 #15
    o kk so is the displacement 400 km/h.... in the beginning i was reading the question wrong i thought it was 1400km/h
     
  17. Sep 22, 2009 #16

    rock.freak667

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    the velocity is 400 km/h


    So on your diagram draw vp and -vA and add them as vectors and you will get your answer.
     
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