Gravity...

Discussion in 'Pseudoscience' started by BdS, Jun 12, 2015.

  1. BdS Registered Senior Member

    Messages:
    512
    When does mass_b contribute to mass_a gravity?

    Im (mass_b) here on Earth (mass_a) and my mass is not fixed to the Earths solid mass, I can move around on its surface. Does my mass still contribute to Earth’s gravitational field?

    Or

    Do I have to be embedded in the Earths solid mass for my mass to contribute to the Earths G field? That would mean that the atmospheres and waters mass doesn’t contribute to Earth’s gravity.

    Or

    Do I just have to be located in Earth’s gravity field for my mass to contribute Earth’s gravity? The moon would be contributing to Earth G then.

    Or

    Does it have to do something with motion or distance?

    Or

    ?



    Gravity is a pain in the...

    When the Earth attracts me does it use my own mass against me? If my mass is contributing to Earths gravity then it does.
     
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  3. Janus58 Valued Senior Member

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    When you have two masses, both masses will always contribute to the gravity field. How they contribute depends on their relative position with respect to each other and the point relative to them where you are measuring the field. If you are far enough away, the gravity field will behave like the total sum of both masses was located at the center of mass for the two objects. For instance, For Mars, it is safe to treat the Earth and Moon as a single mass located at their barycenter. As your distance from the two object gets smaller so that the distance between between them becomes large compared to your distance from them, you have to start treating them as separate gravity sources and combine the effects.

    For instance, with your example of a person standing on the Earth. As far as the Moon is concerned, your mass just adds to that of the Earth. For someone standing next to you, this is not quite the case. For them, there is the mass of the Earth pulling them to the center of the Earth and your mass pulling them sideways towards them. You have to do the vector addition of these two pulls to find the net force and direction. (though because your mass is so small compared to that of the mass of the Earth, your gravity field is so weak even to someone standing right next to you, that the direction of net gravity will still point almost directly to the Earth's center)

    As far as being in the Earth's gravity field, it extends for infinity. So everything is in it. Again, it depends on the distance and position of the objects involved as to just what contribution they make. ( For instance, for a Person standing of the Earth, the Moon can make them either a bit lighter or heavier depending on its position in the sky.)

    When it comes to your mass effecting your own weight. It does in that the force of gravity you feel is due to the product of your and the Earth's mass, so if you have twice the mass, then you have twice the weight. But no, you would not add your mass to that of the Earth and then multiply this sum by your mass to get the force of gravity that you feel.
     
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  5. river

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    17,307
    About the Moon :

    There are many that say the Earths gravity could not possibly capture the Moon . So using the Moon as an example of gravity is mistaken .
     
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  7. Daecon Kiwi fruit Valued Senior Member

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    Citation needed. Again.
     
  8. river

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    Research about the abnomalities of the Moon , the evidence will become clear .
     
  9. Daecon Kiwi fruit Valued Senior Member

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    3,133
    Nope. I'm not putting effort into doing what you should.

    You made the claim, you have to back it up.
     
  10. river

    Messages:
    17,307
    So you are completely ignorant of all the thinking that the Moon should not be captured by the Earth , at all ....? Really .....?
     
  11. Daecon Kiwi fruit Valued Senior Member

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    3,133
    Yeah, let's pretend for the sake of argument that I am.

    Are you going to provide back up for your claim that this is a real train of thought that some people have?

    I'm not going to go searching across the internet for stuff you should easily be able to provide, if your claims are true.
     
  12. river

    Messages:
    17,307
    Lets pretend you knew this all along and there is nothing I need to show you , nor sites I need to give you , you Know .
     
  13. Daecon Kiwi fruit Valued Senior Member

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    3,133
    And that's why you're reported for trolling.
     
  14. billvon Valued Senior Member

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    21,635
    And there are many who believe that summer is caused by Earth being closer to the Sun. Doesn't mean it's true - it just means that ignorance is popular.
    It is an excellent example, since the Earth's gravity affects the Moon (tidal lock, defines its orbit) and the Moon's gravity affects the Earth (tides.)
     
  15. AlexG Like nailing Jello to a tree Valued Senior Member

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    4,304
    Who are the many?
     
  16. paddoboy Valued Senior Member

    Messages:
    27,543

    Are there? Who told you that? an Alien?...or one of those giants you talk about.....or was it Bigfoot!

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    Sure there may be some idiots who would claim that, but that's all they are...Idiots.
     
  17. BdS Registered Senior Member

    Messages:
    512
    I am trying to figure out if a blackhole could be created by all the surrounding masses gravity, it would be the point where all the surrounding masses gravity converge. Like a hybrid point where things would be attracted to the common center of all the mass. Example, all the mass in our galaxy is creating a blackhole in the center of our galaxy by the convergence of all the gravity fields from the surrounding mass.

    I suspect the idea is flawed, because the hybrid point would actually contain no gravity, because you would be pulled in all directions at once and the gross effect would be canceled out. I've read people say that at the center of the Earth you would feel no gravity, because you would be pulled in all directions at once.
     
  18. paddoboy Valued Senior Member

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    27,543
    The main factor with creating a BH, is actually density.
    Any mass, squeezed to within its Schwarzchild radius will become a BH.
    The Earth for instance, if it could be compacted to within 2.5 cms? or thereabouts.......The Sun, if it could be compacted to within about 3kms.
     
  19. BdS Registered Senior Member

    Messages:
    512
    The point where all the fields converge would be dense in gravitational fields and is the point where you would be attracted to.

    I am aware of the normally explanation. Its just an idea I am curious about.
     
  20. BdS Registered Senior Member

    Messages:
    512
    Here on Earth you are always attracted to the center of the Earth, but most of the Earth's mass is not located at the center.
     
  21. Quantum Quack Life's a tease... Valued Senior Member

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    23,328
    Apply this idea to the gravitational anomaly called the "Great Attractor". (maybe win a Nobel in the process

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    )
    Also look up Lagrangian points.
    "culminate center of mass" etc.. might help..
     
    Last edited: Jun 13, 2015
  22. Quantum Quack Life's a tease... Valued Senior Member

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    23,328
    Something of interest maybe: (neutral gravity)

    "DSCOVR will succeed NASA's Advanced Composition Explore's (ACE) role in supporting solar wind alerts and warnings from the L1 orbit, the neutral gravity point between the Earth and sun approximately one million miles from Earth. L1 is a good position from which to monitor the sun, because the constant stream of particles from the sun (the solar wind) reaches L1 about an hour before reaching Earth."

    src: http://www.nesdis.noaa.gov/DSCOVR/
     
  23. origin Heading towards oblivion Valued Senior Member

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    11,888
    The gravitation fields would not coverage at that point. The point you seem to be refering to is the barycenter, which is the point that masses would orbit. If you were a great distance from a binary star system you would be attracted to the system, but inside the orbits of the system you would be attracted to one of the masses and not the barycenter.
     
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