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Thread: if you trow a beam from a plane does it fall vertical or horizontal?

  1. #1 if you trow a beam from a plane does it fall vertical or horizontal? 
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    i cant figure it out


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  3. #2  
    Moderator Moderator Markus Hanke's Avatar
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    Depends where its center of gravity is...


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  4. #3  
    Comet Dust Collector Moderator
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    If you mean a light beam, it goes in whatever direction you point it, subject to refraction by the atmosphere.
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  5. #4  
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    a beam like this I

    so does potential energy tend to spend the faster or the slower?
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  6. #5  
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    Quote Originally Posted by luxtpm View Post
    a beam like this I

    so does potential energy tend to spend the faster or the slower?
    It's not a question of potential energy. If the beam is uniform, the force of gravity acts on its geometric center. If the opposing aerodynamic force acts at the same point, there will be no torque. If it is off center, there will be a torque.

    If the beam is perfectly horizontal, or perfectly vertical, there should not be any difference between the air resistance on one side or the other. If it becomes slightly tilted, I'm not sure exactly what would happen.
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  7. #6  
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    thake this other problem:

    why a beam of density 0.5 floats horizontal if if vertical has identical sunk volume than horizontally

    in a way dinamic sustentation is like buoyancy so iwould expect it to fall horizontally
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  8. #7  
    Universal Mind John Galt's Avatar
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    Do you want to try to ask those sames questions again?

    This time please use English as the chosen language and employ proper grammar and punctuation.
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  9. #8  
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    John, this a rude, even chauvinistic comment

    Not all members here have English as their first language. So what? We welcome members of all nationalities here, even those whose command of English grammar and spelling is not quite to your taste.

    I note that my use of "English English" often differs markedly from those who use American English.

    Do I complain about this? No. I try to unpick (and forgive) what to my purist ears seems a criminal abuse of language by our US cousins.

    So leave off - let luxtpm make his points in peace
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  10. #9  
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    Yeah sorry for my erngrish

    In a way dynamic sustentation is like buoyancy

    So the same a beam of density 0.5 which takes the same sink volume either floating horizontal than vertical floats horizontally, I understand a falling beam will prefer to fall horizontal which points that nature having to chose prefers to spend energy slowly, since this way it will fall slower
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  11. #10  
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    Quote Originally Posted by luxtpm View Post
    Yeah sorry for my erngrish

    In a way dynamic sustentation is like buoyancy

    So the same a beam of density 0.5 which takes the same sink volume either floating horizontal than vertical floats horizontally, I understand a falling beam will prefer to fall horizontal which points that nature having to chose prefers to spend energy slowly, since this way it will fall slower
    It's a completely different situation. If the beam is floating on top of the water, then the side that lifts up out of the water loses its buoyancy, and there is a torque which restores it to the horizontal position. This is not the case for an object falling through the air.
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  12. #11  
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    hum seems you figured it out:

    torque will be greater horizontally than vertical

    so it should fall vertical

    thanks
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  13. #12  
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    Quote Originally Posted by luxtpm View Post
    hum seems you figured it out:

    torque will be greater horizontally than vertical

    so it should fall vertical

    thanks
    Why do you think the torque would be greater horizontally?
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  14. #13  
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    more surface
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  15. #14  
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    There is no more surface on one side of the center of gravity than on the other side.
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  16. #15  
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    well actually if the beam has some thickness it does, as soon as it leans a litle to a side it presents more surface from the cog one side than the other, anyway now you made me unsure ill try to make an experiment

    edit:

    well i did the experiment with a rolling paper and it falls horizontal now i would like to know why
    Last edited by luxtpm; April 10th, 2012 at 05:56 AM.
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  17. #16  
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    Brief series of experiments with a pencil seems to indicate that the orientation of the dropped object does not change unless there is a marked discrepency in air resistence at one end.
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  18. #17  
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    Quote Originally Posted by Sealeaf View Post
    Brief series of experiments with a pencil seems to indicate that the orientation of the dropped object does not change unless there is a marked discrepency in air resistence at one end.
    it should reach terminal velocity

    a pencil doesnt reach terminal velocity at home but a piece of paper does
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  19. #18  
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    As the beam will be subject to turbulence when leaving the plane, it will tumble - except if it has a dent or curve or other such thing stabilizing it in one way.
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  20. #19  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by luxtpm View Post
    a pencil doesnt reach terminal velocity at home but a piece of paper does
    "At home"? You mean if I drop a pencil in the office it will reach terminal velocity, but if I do it in my kitchen, it won't?
    ei incumbit probatio qui dicit, non qui negat
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  21. #20  
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    anyway i figured out by game aviation forums that an uncouncious parachitist falls horizontal
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  22. #21  
    Comet Dust Collector Moderator
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    Yeah, that's a good source for science. Can we get this out of Physics now?
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  23. #22  
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    well i was told by witness how uncouncious chutist fall horizontal
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