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A Question about Object Motions [With thanks in advance]

  1. Apr 9, 2003 #1
    I have a question that puzzle me for a long time!
    This question is:
    a- How an object -either metal or any thing- fly or move in air without changing in its direction.
    b- what field of physics study such matters?
    c- Is there any websites may give me detailed information about my question and its field?

    Thank you very much.
  2. jcsd
  3. Apr 9, 2003 #2


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    I am confused.
    By Newton's 1st law, any object will either remain stationary or move in a constant velocity (and as vector, this includes velocity) unless there is a resultant force acting on it. Simple?
  4. Apr 9, 2003 #3
    Practically, you don't answer my question?

    You only answer the first part of my question,,
    anyhow, I meant how to make an object able to fly in a straight way in air, such as a good rocket?

    Thank you very much
  5. Apr 9, 2003 #4


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    Staff Emeritus
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    Gold Member

    Last edited: Apr 9, 2003
  6. Apr 12, 2003 #5
    actually it's quite simple.
    consider a rocket going strait up.
    we have three coordinates to consider:


    E(z)=F(x)X(y)-F(y)X(x)=-Fmax * Xmax

    Fmax is the gravity pull and Xmax is (R+h) the radius of the earth plus the height of the rocket.
    why there is minus in front?
    cause E(z) is the energy that the rocket gives to the outside.
    -E(z)=Fmax*Xmax is the energy the rocket gets from outside.
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