What's gravity good for?

Discussion in 'Physics & Math' started by arfa brane, Dec 28, 2016.

  1. The God Valued Senior Member

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    Naïveté is what describes you the best.
     
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  3. river Valued Senior Member

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    Speed of the plane
     
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  5. Michael 345 Valued Senior Member

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    Gravity does move the plane up and down accounting for local topography.

    More mass below the plane will pull the plane down.

    Less mass plane will rise.

    This presumes stable speed and still air.

    However in the real world turbulence will far outweigh any minor gravity changes.

    Atmosphere has no effect on frame of reference.

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    Immaterial

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  7. river Valued Senior Member

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    How so ?

    Does not the speed of the plane over come gravity ?
     
  8. Michael 345 Valued Senior Member

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    Yes.

    But speed of plane does not change the strength of the gravity under the plane.

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  9. river Valued Senior Member

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    That's missing the point .

    The speed of the plane over comes gravity ; it seems to me rather obvious .
     
  10. paddoboy Valued Senior Member

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    Not really.....
    The theory of flight is a theory of four opposing forces....
    Weight: the force of gravity
    Lift: Differentials in air pressures, above and below the wings..
    Thrust: Is the force pushing the plane forward.
    Drag: The force of friction and air pressure, opposite the direction of flight.

    The lift created, equals the weight or the force of gravity.
    And the drag, is balanced by the thrust.
    Variations in these forces will see the plane accelerate, slow down, ascend or descend.
     
  11. psikeyhackr Valued Senior Member

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    Starting fusion in stars.
     
  12. paddoboy Valued Senior Member

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    And creating BH's !
    along with just about any cosmological body in the universe!

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  13. river Valued Senior Member

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    Without speed ; enough speed ; the plane will not fly ; simple
     
  14. paddoboy Valued Senior Member

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    Not really river...The current land speed record is probably up around the speed that modern passenger jets fly at...but guess what? They don't fly.
    Again the theory of flight is about four opposing forces:
    Weight/gravity.
    Lift/shape of wings and differential air pressures.
    Thrust, created by the engines.
    Drag, air pressure and friction.

    I mean in reality, you would not explain flight to a kid of 5 years old by saying "because of speed"
     
  15. billvon Valued Senior Member

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    Not nearly as simple as that. Aircraft can fly at zero airspeed without stalling. They can stall (and fall out of the sky) even at very high speeds. There's a lot more to flying than "enough speed."
     

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