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Earth's gravity increasing over time?

  1. Feb 14, 2018 #1

    zuz

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    If the Earth gains 250 tons of weight everyday, over the course of hundreds of years wouldn't this alter the weight of a gram?
     
  2. jcsd
  3. Feb 14, 2018 #2

    PeroK

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    Yes. Have you tried to calculate by how much?
     
  4. Feb 14, 2018 #3

    zuz

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    I wouldn't know where to begin. I never got past high school. My wife was complaining she is gaining weight so I'm just trying to ease her suffering.
     
  5. Feb 14, 2018 #4

    PeroK

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    The relatively small changes in the Earth's mass over time don't amount to a measurable difference in weight. Unlike eating a New York style cheescake!
     
  6. Feb 14, 2018 #5

    jim mcnamara

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    If your wife weighs herself at different times of day or on different scales, it will not be useful especially for people who are very oriented to weight-watching.
    Use one scale, at the same time every day, if the daily weigh-in is the preferred schedule. Best time is when the person just wakes.

    Menstrual cycles, pregnancy, diet, sodium content of foods, and a range of minor and major disorders - all can alter the value with out the subject changing adipose tissue (fat) - i.e., weight goes up or down.

    People sometimes have the destructive view that 'I should always weigh exactly X pounds'. Which is not always a good concept.
    https://www.ncbi.nlm.nih.gov/books/NBK221834/
     
  7. Feb 14, 2018 #6

    CWatters

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    Unfortunately Google suggests the earth is loosing more mass than it gains so gravity is getting weaker.

    Perhaps she used to live nearer the equator?
     
  8. Feb 14, 2018 #7

    russ_watters

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    Newton's gravity equation should be usable by anyone with a high school education. That's all you need.
     
  9. Feb 14, 2018 #8
    zuz, Even if you are correct about Earth adding 250 Tons of mass every day that would be equivalent to adding an amino acid molecule to you wife's forehead once a year.

    Russ_Watters I think you need to look at: https://en.wikipedia.org/wiki/List_of_equations_in_gravitation This is a place one would actually look and would scare off all but AP Physics and Math high school students. Your response was something of a put off.
     
  10. Feb 14, 2018 #9

    Tom.G

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    Yes, so poorly presented it certainly would!
     
  11. Feb 15, 2018 #10

    PeroK

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    Actually, if the Earth gains mass, then its gravity at the surface will decrease; and, if it loses mass, then its gravity will increase.

    This is because Earth is denser at the core and if it gains or loses mass at the surface it will also increase or decrease in size. At the moment, if you tunnel down inside the Earth, the gravity will increase, as you are getting closer to the dense core. Therefore, if you removed a layer from the surface of the Earth, then you would be closer to the dense core and the surface gravity would increase. Likewise, if you added a layer to the surface, the surface gravity would decrease.

    See, for example:

    https://en.wikipedia.org/wiki/Gravity_of_Earth#Depth
     
  12. Feb 15, 2018 #11
    But losing some mass from the atmosphere will affect only the orbital mechanics, while gathering some space dust to the surface will indeed increase surface gravity...
     
  13. Feb 15, 2018 #12

    PeroK

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    ... decrease the surface gravity. See post #10.
     
  14. Feb 15, 2018 #13
    Well, if we want to dig that deep then it'll depend on the density of that dust...
     
  15. Feb 15, 2018 #14

    PeroK

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    ... by "dig deep", you mean get the right answer?
     
  16. Feb 20, 2018 #15
    the earth gains mass at it's gravitional point (the actual earth, not it's atmo..
    So, there's an increase of the earth's mass, and therefore an increase of gravity..

    But also, as the earth shrinks slightly (cooling down center, albeit very slowly)
    The density of the earth increase slightly as well, decreasing the distance to the earth's overall mass..
    Shorter distance, higher field density => more gravity exerted on you as person as well..

    The increasing mass at ground is so small it would takes mllions of years to be noticeable I'd say..
    (or at least thousands)
    I hope the Earth never really cools enough to actually have non-spinning metal layers though (although over time
    this very possible), because then questions like gaining or losing weight would be the least of our concerns..

    (also, the earths atmo may yet gain as well as lose..dependant on the particles that get blasted off
    having enough velocity under a certain vector to really escape the earth's gravity, without ever returning..)
    (however, most particles do return to the fold..)
     
  17. Feb 21, 2018 #16

    davenn

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    that is incorrect ... if you think it is correct please provide a good citation
    Mass loss from the atmosphere each year is ~ 40,000 - 50,000 tonnes round figures depending on different reports



    https://phys.org/news/2016-07-curious-case-earth-leaking-atmosphere.html
    https://scitechdaily.com/earth-loses-50000-tonnes-of-mass-every-year/

    none of the many papers I have read talk about any of it "returning to the fold"[/QUOTE]
     
  18. Feb 21, 2018 #17
    Returning to the fold is a figure of speech, and I have no quote. I simply reasoned it..

    Gravity still attracts even when a sufficient impact by solar winds gives speed under a certain vector
    when the atmo particles get 'hit'..
    Even so, Earth's gravity will keep attracting them, and thus pull them back into the atmosphere,
    when the vector is away from Earth.
    Then when the intial vector is being changed by Earth's gravity (and it's speed), the particle may yet
    'return to the fold' =>return to the atmosphere and be part of it once again..
    Only when the particle's vector and speed is great enough to actually escape Earth's gravity,
    (either by initial impact or sum off repeated impacts by solar wind particles) does it truly leave
    Earth's sphere completely, with a few exceptions like being sent into a path that will later
    lead it back to Earth..

    Also, if the Earth's H layer would have been losing H particles like that it would have lost roughly 200
    teratonnes of H particles over time (an even greater estimate has been made by me)
     
  19. Feb 21, 2018 #18

    davenn

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    again, that isn't happening, hence the large tonnage of loss

    if you think otherwise ... please provide good references
     
  20. Feb 21, 2018 #19
    Why should I ? All you did is take someone else's earlier concluded, possibly flawed, calculations
    and stated them for fact..

    The entire (simplified) model I gave is correct..

    {unsubstantiated claims deleted}

    So, it DOES occur. No citation or reference required..
     
    Last edited by a moderator: Feb 23, 2018
  21. Feb 21, 2018 #20

    davenn

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    Why ?
    because you are making claims that are unsubstantiated.
    no, I took established facts and backed them up with a couple of out of dozens of references

    PF is a science based forum we like comments/claims to be backed up with good references
    If you are unable to do that, you will find it difficult for people to take you seriously here


    Dave
     
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