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Layers of gravity and kinetic force - us to galaxy

  1. Sep 23, 2010 #1
    Where there's a query, there's a forum! I'm glad I found this place.

    So here's my quandary. The earth is rotating. It's orbiting the sun. Our solar system drifts through the galaxy which galaxy is drifting through the universe. Supposedly, even though I stand still, I'm moving in some strange, undefined, curved/wobbly path through the universe.

    Is it all relative? When a plane flies in it's curved path around the earth, does the rotation of the earth or it's orbit influence the path of the plane? Does the gravity bubble we live in some how zero out the rest of the universe so when we do tests involving kinetic energy and things moving, it's all relative to us so that no matter if we're hurdling through the dark, something is either moving or not moving relative to us? Can we somehow detect the layers of force that work on us or are we so far down at the bottom of the totem pole of it all that any force that moves our world any beyond is irrelevant?

    Is there another question I have not asked that I should be asking that can be answered? I'd like to know what that is too. Where does gravity play in all this? If the earth is rotating, don't I have some kinetic energy in play, but because of the fact that any instrument to test that is moving too, that it zeros out the rotation of earth, orbit, system and galaxy drift?

    You'd think I could just go play StarCraft or watch a movie, but no, the secrets of the universe demand to be answered! And I had to come here to find some understanding of it all.

    Thank you for anyone who can break apart this kinetic onion.
    Last edited: Sep 23, 2010
  2. jcsd
  3. Sep 23, 2010 #2


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    In theory, yes. The Earth's rotation has a tiny, tiny effect on our apparent weight.

    Orbit, no.

    The Earth's orbit is indeed deflected a small amount by nearby masses such as Jupiter. Wobbles in some of our outer planets actually lead to the discovery of heretofore unknown planets.

    Theoretically, Earth experiences Jovian tides. I'm not sure if anyone has goen toe trouble of trying to detect them though.

    No. Astromomical calculations must be carefully performed to eliminate these tiny factors or they will show up in the data.
  4. Sep 24, 2010 #3
    Thanks for some of your insight. I'm still a little overwhelmed by it all. I did find a similar thread which shows that apparently I'm not alone in the universe on wondering about these things.


    Just a few things in response which may show a little more about what my babblings were leading to. The wobbling thing was just referring to what 1 person's path would look like if you were to attempt to plot that path through space which I understand would be quite impossible to even display.

    But I do wonder how the path of the earth, it's rotation, the movement of the solar system and galaxy affect us. Not us as in the whole planet when influenced by other masses, but me, you and everyone else. Does the velocity and vector of these larger things mentioned affect people in any perceivable, measurable way.

    After thinking about it, it almost seems the answer is no or people building a towering house of playing cards would never finish and people couldn't ride unicycles. Any other thoughts?
  5. Sep 24, 2010 #4


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    The short answer is: some do, some don't. The ones that do have a vanishingly small effect.

    For example: Jupiter is pulling on us, it pulls Earth's orbit away from its normal path. However, it is pulling on both Earth and us equally. So, despite the fact that Earth may be a few thousand km from its proper location than if Jupiter weren't there, we too on Earth are also pulled, meaning that our relation to Earth is undisturbed.

    In the same sense, an astronaut in the space shuttle is whizzing around the Earth in a tight circle every 90 minutes, but when he drops a screwdriver, it does not take off toward the nearest wall. Both astronaut and screwdriver are in the grips of the same forces, so the net effect is zero. And it is these net effects that we feel.

    You do not feel forces unless they are being resisted. When you are in a freefalling elevator, you do not feel gravity - you feel weightless - no forces acting on you. When the elevator slows and stops is when you feel the force (the elevator pushing you up as it slows).
  6. Sep 24, 2010 #5
    Ah! Thank you very much for entertaining my scientific inquiry. I hope to return here with any other questions of physic as I have never had a class on the subject, but wish I had.
  7. Sep 24, 2010 #6


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    You are very welcome here. We will fall over ourselves to answer your questions.
  8. Sep 24, 2010 #7
  9. Sep 24, 2010 #8


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    Well, sorta but notice they say:

    It's this very thing that the OP is interested in.
  10. Sep 24, 2010 #9
    to answer the op
    the only forces that you would actually have to worry about are tidal forces.
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