Earth's gravity increasing over time?

[zuz]

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?

 

[PeroK]

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?

Yes. Have you tried to calculate by how much?

 

[zuz]

Yes. Have you tried to calculate by how much?

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.

 

[PeroK]

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.

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!

 

[jim mcnamara]

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 without 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/

 

[CWatters]

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?

 

[russ_watters]

I wouldn't know where to begin. I never got past high school.

Newton's gravity equation should be usable by anyone with a high school education. That's all you need.

 

[Gary Feierbach]

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.

 

[Tom.G]

would scare off all but AP Physics and Math high school students.

Yes, so poorly presented it certainly would!

 

[PeroK]

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

 

[Rive]

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

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...

 

[PeroK]

while gathering some space dust to the surface will indeed increase surface gravity...

... decrease the surface gravity. See post #10.

 

[Rive]

... decrease the surface gravity. See post #10.

Well, if we want to dig that deep then it'll depend on the density of that dust...

 

[PeroK]

Well, if we want to dig that deep then it'll depend on the density of that dust...

... by "dig deep", you mean get the right answer?

 

[ZMacZ]

the Earth gains mass at it's gravitational 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 Earth's atmo may yet gain as well as lose..dependent 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..)

 

[davenn]

(also, the Earth's atmo may yet gain as well as lose..dependent 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..)

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]

 

[ZMacZ]

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

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)

 

[davenn]

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..

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

if you think otherwise ... please provide good references

 

[ZMacZ]

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

if you think otherwise ... please provide good references

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..

 

[davenn]

Why should I ? All you did is take someone else's earlier concluded, possibly flawed, calculations
and stated them for fact..

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 hereDave

 

[hutchphd]

... decrease the surface gravity. See post #10.

Clearly if the new material is sufficiently dense, the surface gravity will increase with accretion of this new layer. If I did the arithmetic correctly the new material layer must have a density greater than 2/3 the average density of the existing earth. This assumes spherical symmetry.

 

[PeroK]

Clearly if the new material is sufficiently dense, the surface gravity will increase with accretion of this new layer. If I did the arithmetic correctly the new material layer must have a density greater than 2/3 the average density of the existing earth. This assumes spherical symmetry.

As things stand gravity increases as you go below the Earths surface. If you added a further surface layer the same would apply - almost certainty. You'd need the new surface to have unusual density.

 

[hutchphd]

As things stand gravity increases as you go below the Earths surface. If you added a further surface layer the same would apply - almost certainty. You'd need the new surface to have unusual density.

I guess I don't understand what you mean by "unusual" density. The average specific density of planet Earth is about 5.5, so the accretion of stuff denser than ~3.7 g/cc (2/3 of 5.5) will cause an increase in g. Do we know what "usual" stuff is?

 

[PeroK]

I guess I don't understand what you mean by "unusual" density. The average specific density of planet Earth is about 5.5, so the accretion of stuff denser than ~3.7 g/cc (2/3 of 5.5) will cause an increase in g. Do we know what "usual" stuff is?

The Earth does not have uniform density. The core is significantly denser than the surface. If the new surface material is similar in density to the current surface density...

 

[hutchphd]

The Earth does not have uniform density. The core is significantly denser than the surface. If the new surface material is similar in density to the current surface density...

If that is true then we agree. I would point out that the Earth is a dynamic system (fluid) and the light stuff rises to the surface. Since the Earth was formed by accretion, its average density seems a better estmate for the incoming matter than the surface material which has been fractionally separated by the planet.

I'm sure somebody knows the true answer!