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Homework Help: Plane flying at an angle, trying to find radius

  1. Oct 17, 2008 #1
    1. The problem statement, all variables and given/known data
    To change the direction of the plane, its wings are banked. If the wings of the plane are banked 50.0° to the horizontal, what is the radius of the circle in which the plane will be flying? Assume that the speed remains 480.0 km/h during the turn and that the magnitude of the lift provided by the wings is unchanged.



    2. Relevant equations
    m = 13900kg (given previous to this problem) but I do not think this comes into play

    3. The attempt at a solution
    I said that the forceof the lift = L. the sum of forces in the y direction = Lcos50 = mg. The sum of forces in the x direction = Lsin50 = (mv^2)/r. Solving both equations for L and then setting these expressions equal to each other, I eventually came to r = (v^2)/gtan50, giving me an answer of 19,707km. The computer keeps telling me I am incorrect.

    Any help would be appreciated
     
  2. jcsd
  3. Oct 17, 2008 #2

    Doc Al

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    Staff: Mentor

    Be careful with units. That speed is given in km/hour--convert to standard units.
     
  4. Oct 17, 2008 #3
    still wrong
     
  5. Oct 17, 2008 #4
    that gave me an answer of 1521m, which seems kind of small anyway
     
  6. Oct 17, 2008 #5

    Doc Al

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    Looks right to me.
     
  7. Oct 17, 2008 #6
    so do you think that it could possibly be an error with the computer? I can't see any mistake I have made.
     
  8. Oct 17, 2008 #7

    Doc Al

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    It wouldn't surprise me, as those systems can be fussy. What units does it want? How many significant figures?
     
  9. Oct 17, 2008 #8
    It does no specify what units it wants, or how many significant figures. I have tried many combinations of both.
     
  10. Oct 18, 2008 #9

    Doc Al

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    Oops. I missed the implication of this:
    So the following is incorrect:
    This (the last sentence) is not true. Once the plane banks there is no longer vertical equilibrium.

    My bad! :redface:

    Your bad: Please post the entire problem.

    (Thanks to alphysicist for waking me up! :smile:)
     
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