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Homework Help: Forces on an aircraft

  1. Dec 15, 2009 #1
    1. The problem statement, all variables and given/known data

    This was from a recent paper we did in class, I've tried to re-create the drawing as best I can.

    http://img94.imageshack.us/img94/378/14264945.jpg [Broken]

    The options were (I think)

    a) 10n
    b) 6n
    c) 4n
    d) 2n

    2. Relevant equations

    Not sure

    3. The attempt at a solution

    I'm not sure how to work out the missing force
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Dec 15, 2009 #2


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    Do you know how to draw a vector diagram? None of the choices are correct because the answer has to be greater than 10 N (the 6 N can't have no effect).
  4. Dec 15, 2009 #3
    Sorry, I'm not sure how to do that, had a look in goggle and some text books, but got nothing simple. I'm 11, and this is beyond the scope of my current course at school, this was off a paper from ground school (flight school), I'm trying to get to grips with it in my spare time to aid my ambition of becoming a pilot.

    If you could help me out I'd appreciate it, thanks for your time.
  5. Dec 15, 2009 #4
    so what you are looking here is

    Force of gravity pointing downwards, that's your 6n and your ten newtons is your force air resistance. now you have to find the vector for you which is your x. do you know about vectors at all?
  6. Dec 15, 2009 #5


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    Sorry, but that's just plain wrong. Can 6N reasonably be gravity? Is the 10N even in the right direction to be air resistance?

    justice: adding vectors (which is what forces are) is similar to adding displacements. If you walk 6m "down" and 10 m forwards, how far have you walked in total? Hint: You'd use the Pythagorean theorem to figure it out. Whatever number you get is the answer to the question (the only thing that's different is the name of the unit).
  7. Dec 15, 2009 #6
    maybe im wrong but isnt the 6n the Net force in the y direction? so it involves the upwards force and gravity

    and isnt the only force the plane will be encountering in the 10n direction air resistance? i assume trhe plane is going forwards. :)

    pythagorean is c^2= a^2 + b^2 by the way

    if you look at it like a triangle then you are trying to find the hypotenuse i believe.

    Edit: oh wow im stupid. of course its not air resistance. air resistance points in the opposite direction. your 10n is your net force of the plane in the x direction. lol im an idiot.
  8. Dec 16, 2009 #7
    So the answer would 10^2 + 6^2 = 136

    and then find the square root of 136? This would come out to a decimal though and I'm sure there was no answer with a decimal.
  9. Dec 16, 2009 #8
    Can anyone confirm the above method is correct?
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