Gravity At The Center Of The Earth

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Offline neilep

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« on: 06/05/2007 16:41:41 »
Hmmm..perhaps this should be in the Physics section !!

I think it should but will allow someone else to move it because I'm lethargic right now.



Say for instance there was conditions at the center of the Earth that could sustain Human life from an environmental pint of view (Very unlikely I know)......but it it were possible.

What would the conditions be like ?..would I float about in a a gravity-less state ? or would I be pulled apart or squashed ?....or something else ?
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paul.fr

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« Reply #1 on: 06/05/2007 17:00:45 »
that depends on what you mean by centre of the earth! if you were to drill a hole/tunnel from one point on the earth to another, at the very centre of that hole/tunnel you would not feel the pull one way or the other. if you were slightly off centre then thats another question.

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Offline neilep

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« Reply #2 on: 06/05/2007 17:09:39 »
that depends on what you mean by centre of the earth! if you were to drill a hole/tunnel from one point on the earth to another, at the very centre of that hole/tunnel you would not feel the pull one way or the other. if you were slightly off centre then thats another question.


Yep..I mean right at the center....so If I don't feel any pull...does  that mean the pressure inside my body will explode me ?

I imagine there would be a large enough area where the gravity is slight either way to enjoy flying fun !!
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Offline Seany

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« Reply #3 on: 06/05/2007 17:18:51 »
Neily... If you go underwater that deep.. Our lungs explode and all our internal organs, because of the pressure. Imagine under all that water, and near the core of the earth?
They say that when you die, your life flashes in front of you. Make it worth watching!


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Offline neilep

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« Reply #4 on: 06/05/2007 17:25:05 »
Hmmm..Thanks Seany !!..what happens if we dismiss the pressure thingy ?...will it be ok to have fun at the center of the earth ?
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Offline Seany

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« Reply #5 on: 06/05/2007 17:26:59 »
Err.. Apart from the intense heat........ Err.. Maybe?

Oh.. Also the gravity would be stronger there, so we might still get squashed.. Like, so that we're the size of a pen.. So we'll still probably die. [;)]
They say that when you die, your life flashes in front of you. Make it worth watching!


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Offline neilep

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« Reply #6 on: 06/05/2007 17:52:41 »
Err.. Apart from the intense heat........ Err.. Maybe?

Oh.. Also the gravity would be stronger there, so we might still get squashed.. Like, so that we're the size of a pen.. So we'll still probably die. [;)]

That's not nice !!..me does not want to die at the center of the Earth.... [;)]


Ok....lets change the 'object ' of the question.

Say I had a football made out of something which is impervious to heat, pressure and anything else that has a tendency to make conditions intolerable.....and that there was a cavity the size of football pitch (cubed) in the center of the Earth.....what would happen to the ball ?
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another_someone

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« Reply #7 on: 06/05/2007 18:15:26 »
Neily... If you go underwater that deep.. Our lungs explode and all our internal organs, because of the pressure. Imagine under all that water, and near the core of the earth?

Actually, if anything, your lungs will implode rather than explode, but that is only if you do not equalise air pressure within them.  The bigger problem you have is the effect of gasses dissolving into the blood at high pressure having all sorts of physiological effects.

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Offline that mad man

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« Reply #8 on: 06/05/2007 18:18:15 »
If you were able to be at the very centre then I think the gravity would be zero so the ball would be weightless and float.

Bee




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another_someone

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« Reply #9 on: 06/05/2007 18:24:19 »
The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth, since the amount of matter around you is no greater than the amount of matter beneath your feet when you are at the centre of the Earth.

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.

What will be an issue is not the nett gravitational pull, but the gravitational tidal forces (although I doubt these will be enough to cause genuine harm to you).  What I mean by the tidal forces is that on the surface of the Earth, the gravitation pull at any point, and at a point about 1 centimetre away from that point, will be very similar, so although gravity will effect all parts of your body, it will effect it equally.  At the centre of the Earth, the gravitational pull at one point may be very different from the gravitational pull at another point close by; so although the actual gravitational pull will only be small, it could nonetheless be pulling your head in one direction, your feet in another, and your arms elsewhere.  Our bodies were not designed to be pulled apart like that, although because of the very small forces actually doing the pulling apart, it may not actually do any more harm than maybe cause motion sickness.

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Offline JimBob

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« Reply #10 on: 06/05/2007 19:31:23 »
I believe what everyone is missing is that the null point for gravitational forces at the center of the earth is just that - a point. Around that null point is molten metal under enormous pressure - millions of PSI - and since nature abhors a vacuum that single pint will already be occupied. The pressure at that depth would overcome any tidal forces as would the compounded angular momentum of all the material above you. I doubt your chances of survival are not good. No, not good at all. Bye, bye, my friend.  [:0]
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Offline neilep

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« Reply #11 on: 06/05/2007 20:27:45 »
Jimmy Boy....my question allows for the facility for it to be of a hospitable nature !!

So, it would not be " bye bye my friend "..it would  " come on over and have some fun friend"...YAYYYYYYYYY !!!
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Offline JimBob

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« Reply #12 on: 06/05/2007 22:16:11 »
Ok, science fiction time, huh?
The mind is like a parachute. It works best when open.  -- A. Einstein

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another_someone

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« Reply #13 on: 07/05/2007 01:03:42 »
Ok, science fiction time, huh?

A more charitable description would be a Gedankenexperiment [:)]

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jolly

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« Reply #14 on: 07/05/2007 10:03:28 »

That's not nice !!..me does not want to die at the center of the Earth.... [;)]


Ok....lets change the 'object ' of the question.

Say I had a football made out of something which is impervious to heat, pressure and anything else that has a tendency to make conditions intolerable.....and that there was a cavity the size of football pitch (cubed) in the center of the Earth.....what would happen to the ball ?

It would sit on the central spot- in the middle of the pitch and not move anywhere!

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jolly

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« Reply #15 on: 07/05/2007 10:14:03 »
The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth,

May I ask how you know that?

since the amount of matter around you is no greater than the amount of matter beneath your feet when you are at the centre of the Earth.

This explaination is about the center of the earth not the crust!


In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.

I do not agree with this statement! As I feel the Earths gravity is created by more than just mass!

What will be an issue is not the nett gravitational pull, but the gravitational tidal forces (although I doubt these will be enough to cause genuine harm to you).  What I mean by the tidal forces is that on the surface of the Earth, the gravitation pull at any point, and at a point about 1 centimetre away from that point, will be very similar, so although gravity will effect all parts of your body, it will effect it equally.  At the centre of the Earth, the gravitational pull at one point may be very different from the gravitational pull at another point close by; so although the actual gravitational pull will only be small,

I feel that this is incorrect as the gravitational pull from the earth will increase the closer you get to the center realitive to your mass!

it could nonetheless be pulling your head in one direction, your feet in another, and your arms elsewhere.  Our bodies were not designed to be pulled apart like that, although because of the very small forces actually doing the pulling apart, it may not actually do any more harm than maybe cause motion sickness.

Considering the fact that we hav'nt been there and the idea of going there is far to risky considering we could damage the earths. This is assumption but I like it.X
« Last Edit: 07/05/2007 10:19:59 by jolly »

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another_someone

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« Reply #16 on: 07/05/2007 11:19:16 »
The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth,

May I ask how you know that?

The same way that I know the Sun will rise tomorrow - I extrapolate from what I do know into what I do not know.  I may be wrong, maybe the Sun will not rise tomorrow, despite my experience of every previous morning when I have observed the Sun to rise, it may yet prove that my extrapolation of existing knowledge will prove to be false; but if we do not extrapolate based upon what we do know, then we are simply left with a total absence in our ability to predict anything - which serves us no good whatsoever.

I feel that this is incorrect as the gravitational pull from the earth will increase the closer you get to the center realitive to your mass!

We have drilled holes into the surface of the Earth, and nobody has reported anything that contravenes expectations with regard to gravity as we dig beneath the surface.  It is true that we have not dug very deep into the Earth, but we have some very sensitive instruments that can easily detect even the small changes of gravity that one would expect to occur as we dig a few kilometres beneath the Earth.

Furthermore, we can, on the surface of the Earth, actually detect the gravitational fields emitted by individual mountains - if all of the Earth's gravity was emanating from its centre, then we should not be able to sense any gravity emanating from surface features such as mountains.

In one respect, there might be one effect in which you have some validity, in that as you get closer to the centre of the Earth, because of the hight pressures, one would expect the density of the matter around you to increase (although the pressure will also be offset by higher temperatures, which will limit any increase in density).  More dense rock will have a greater gravitational pull, but this has to be offset by the fact that you still have more of that rock above you than below you.

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.

I do not agree with this statement! As I feel the Earths gravity is created by more than just mass!

Would you like to provide some more detail as to what you think, aside from mass, is creating this gravity; and provide some mathematical model as to how this force would behave throughout the universe (something that can actually be tested against observation)?

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jolly

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« Reply #17 on: 07/05/2007 14:15:40 »

The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth,

May I ask how you know that?

The same way that I know the Sun will rise tomorrow - I extrapolate from what I do know into what I do not know.  I may be wrong, maybe the Sun will not rise tomorrow, despite my experience of every previous morning when I have observed the Sun to rise, it may yet prove that my extrapolation of existing knowledge will prove to be false; but if we do not extrapolate based upon what we do know, then we are simply left with a total absence in our ability to predict anything - which serves us no good whatsoever.

Yeah what do you actually believe?


I feel that this is incorrect as the gravitational pull from the earth will increase the closer you get to the center realitive to your mass!

We have drilled holes into the surface of the Earth, and nobody has reported anything that contravenes expectations with regard to gravity as we dig beneath the surface.  It is true that we have not dug very deep into the Earth, but we have some very sensitive instruments that can easily detect even the small changes of gravity that one would expect to occur as we dig a few kilometres beneath the Earth.

My I ask how your instruments check for gravities effect?

Furthermore, we can, on the surface of the Earth, actually detect the gravitational fields emitted by individual mountains - if all of the Earth's gravity was emanating from its centre, then we should not be able to sense any gravity emanating from surface features such as mountains.

well thats a huge assumption!
Afterall mountains and volcanos are attached to the earth and esspecally in the case of volcanos- they have a direct line connection to the core and magma.


In one respect, there might be one effect in which you have some validity, in that as you get closer to the centre of the Earth, because of the hight pressures, one would expect the density of the matter around you to increase (although the pressure will also be offset by higher temperatures, which will limit any increase in density).  More dense rock will have a greater gravitational pull, but this has to be offset by the fact that you still have more of that rock above you than below you.

Well again surely in liquid form an object of big mass fills a smallier space- as there for a start will not be any air within it for example!

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.

I do not agree with this statement! As I feel the Earths gravity is created by more than just mass!

Would you like to provide some more detail as to what you think, aside from mass, is creating this gravity; and provide some mathematical model as to how this force would behave throughout the universe (something that can actually be tested against observation)?

Sorry to be a prude but I am not prepared to discuss what I feel is the reality- with regards to Gravity.
This may upset you... but I feel that we should talk in current scientific terms and not take a new theory line!   
« Last Edit: 07/05/2007 20:03:55 by jolly »

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Offline Bored chemist

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« Reply #18 on: 07/05/2007 15:08:20 »
Jolly, since your last "theory" about gravity ended up in the "new theories" section I think it's a bit rich for you to say "but I feel that we should talk in current scientific terms and not take a new theory line! ".
Also, our statement "I do not agree with this statement! As I feel the Earths gravity is created by more than just mass!" is, in fact an indication that you have a new theory about gravity which differs significantly from the current one scientists have been using for centuries. You are the one taking up new theories.

Also re "My I ask how your instruments check for gravities effect?"
probably like this
http://en.wikipedia.org/wiki/Gravimeter

OK, enough of "Jolly world" and back to the question.
If you were to drill a big hole thought the earth and line the "tunnel" with some magic sort of bricks that would prevent a cave in  (or, more plausibly, get a very old planet that has cooled down enough so the job gets a lot easier and drill a hole in that) then you would get a gradual reduction in the effect of gravity as you went down the tunnel to the centre of the earth then a gradual increase the other way as you went back to the surface. The variation of the force of gravity is linear with distance from the centre This result was first calculated be Newton and assumes that the density of the earth is constant- unlikely in reality but probably close enough. It also means that, neglecting air resistance, if you dropped something down the "hole" it would bounce back an to exhibiting simple harmonic motion. More importantly (at least for the purposes of this discussion), because your height is only a tiny fraction of the distance from the centre of the earth to the surface you would be pulled apart by only a tiny fraction of 1 g. The force would be something like a hundredth of a gram (OK, that should be in Newtons, but what we are talking about is the weight of a postage stamp). Even in a big "flying cave" the forces would be small so, yes Neil, you could float about like a spaceman.
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jolly

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« Reply #19 on: 07/05/2007 15:35:36 »
Sorry Chemist, but I am not engaging with you about anything other than chemistry.....
And as I dont really care if milk stablizes me coffee- There's no need to chat.... I mean have'nt you got some water to de-gas or something?

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Offline Bored chemist

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« Reply #20 on: 07/05/2007 16:40:41 »
Does that mean other people only have to engage with you about jollity, seems like a good idea, or is it that when you engage with me about other things you come off looking like you don't know what you are talking about?
What does "And as I dont really care if milk stablizes me coffee" mean, or are you not going to answer because it's not chemistry?
« Last Edit: 07/05/2007 16:42:14 by Bored chemist »
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jolly

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« Reply #21 on: 07/05/2007 17:53:31 »
Not It means I am tired of listening to your comments and links relating to things you, I dont think really understand!

My post was to another someone not you!

But yet again you feel the need to come in and start posting rubbish as usual- and your probably gonna starting going on about how I'm trolling! blar blar blar!

No doubt ukmickey will be in, in a minute to close it!
« Last Edit: 07/05/2007 17:59:36 by jolly »

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Offline Bored chemist

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« Reply #22 on: 07/05/2007 20:00:15 »
If you want to send a message to an individual like Another Someone then pm them. If you post stuff on an open forum it will be read by many and may be replied to by anyone who is logged in.
I'm sure others here will come to  their own conclusions about who is posting rubbish (like And as I dont really care if milk stablizes me coffee" and whether or not you are trolling.
BTW, why don't you think I understand gravity at least as well as you do? At least my understanding of it tallies with real life.
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jolly

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« Reply #23 on: 07/05/2007 20:04:39 »
Whatever Bored   Anyway moving on.....


The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth,

May I ask how you know that?

The same way that I know the Sun will rise tomorrow - I extrapolate from what I do know into what I do not know.  I may be wrong, maybe the Sun will not rise tomorrow, despite my experience of every previous morning when I have observed the Sun to rise, it may yet prove that my extrapolation of existing knowledge will prove to be false; but if we do not extrapolate based upon what we do know, then we are simply left with a total absence in our ability to predict anything - which serves us no good whatsoever.

Yeah what do you actually believe?


I feel that this is incorrect as the gravitational pull from the earth will increase the closer you get to the center realitive to your mass!

We have drilled holes into the surface of the Earth, and nobody has reported anything that contravenes expectations with regard to gravity as we dig beneath the surface.  It is true that we have not dug very deep into the Earth, but we have some very sensitive instruments that can easily detect even the small changes of gravity that one would expect to occur as we dig a few kilometres beneath the Earth.

My I ask how your instruments check for gravities effect?

Furthermore, we can, on the surface of the Earth, actually detect the gravitational fields emitted by individual mountains - if all of the Earth's gravity was emanating from its centre, then we should not be able to sense any gravity emanating from surface features such as mountains.

well thats a huge assumption!
Afterall mountains and volcanos are attached to the earth and esspecally in the case of volcanos- they have a direct line connection to the core and magma.


In one respect, there might be one effect in which you have some validity, in that as you get closer to the centre of the Earth, because of the hight pressures, one would expect the density of the matter around you to increase (although the pressure will also be offset by higher temperatures, which will limit any increase in density).  More dense rock will have a greater gravitational pull, but this has to be offset by the fact that you still have more of that rock above you than below you.

Well again surely in liquid form an object of big mass fills a smallier space- as there for a start will not be any air within it for example!

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.

I do not agree with this statement! As I feel the Earths gravity is created by more than just mass!

Would you like to provide some more detail as to what you think, aside from mass, is creating this gravity; and provide some mathematical model as to how this force would behave throughout the universe (something that can actually be tested against observation)?

Sorry to be a prude but I am not prepared to discuss what I feel is the reality- with regards to Gravity.
This may upset you... but I feel that we should talk in current scientific terms and not take a new theory line!   
« Last Edit: 08/05/2007 13:21:49 by jolly »

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Offline JimBob

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« Reply #24 on: 08/05/2007 02:42:43 »
Ignore this person when he/she/it starts "trolling."
The mind is like a parachute. It works best when open.  -- A. Einstein

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jolly

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« Reply #25 on: 08/05/2007 13:46:39 »
Would you like to provide some more detail as to what you think, aside from mass, is creating this gravity; and provide some mathematical model as to how this force would behave throughout the universe (something that can actually be tested against observation)?

well going against my better nature.. ANOTHER_SOMEONE


RIGHT.....

Giving the earth and moon astronomical units = to 500km per unit!

Gives us around 77- AU

For the sun during Earths sotheren H. winter is around- 299000 AU
And during the sothern H. Summer around- 290030 AU
A Difference of- 8970 AU

The luna orbit would be around- 242 AU

If the earth has a solar unit of 9
The moon would be around 1.5- SU

The earths axis 23.5 stays realtively the same- always faces the same direction- In the southern winter it faces towards the sun and in the southern summer it faces away- so it stays faceing the same dirrection as we move around the sun! There would probably be a greater axis wobble during the summer- due to the sun pushing the earth not pulling it!

Do not forget that the sun moves at 42,000 mph.
So for the earth to over taken it and complete a full orbit in the year time frame, it would travel around 82,000 mph in southern H. spring and autum and then in the summer and winter slow to between 55,000 to 57,000 mph- During the summer and winter the earth it's fighting against the sun; moving forward or back and across. Where as in the spring and autum- it is not- allowing for the increase in speed! 

Right now

The magnetics of the earth and moon repel each other.
The Wb of a magnet faced- 3cm by 5cm is= 30 x 10‾6Wb
I cannot be bothered to Go work out the Wb of the earth
and moon- But you clearly like playing with numbers So go for it!

But you could use the SU for that to a degree!

The solar wind which travels at around 69,120,000km/h also acts to push the moon away from us- or around us! The wind also affects the earth(friction) but hits both sides evenly and therefore is a netural force- our atmosphere and gravity- to a degree protects us! The moon has neither!

Now the moon has no gravity and is pulled towards the Earth by our gravity!

Magnetics and the Solar wind both act to repel the moon- And as the earth magnetic field changes- Due to the core cooling down, the moon is being pushed ever so slowly thurther away from us!

The Tide is repelled by the moon as it passes over!
The moons position shifts as the earths magnetic poles move!

So you have Gravity pulling the moon towards the earth and magnetics and solar wind pushing it away!

The magnetics of the earth is changing- And as a result can no-long force heat from the poles as it did.. ergo that is why the poles are melting- If you do not believe that magnetic can affect the temperture of an area- I would point to sun spots... Which are heavy areas of magnetics on the sun which reduce the temperture and cause these black spots to appear! Iron and nickel- Iron magnetics increases as the core cools and nickel magnetics decreases as the core cools!
The sun spots are probably produced by Nickel!

So MR(E + M) + SW = R = Force of luna repulsion
 R - EG = W = Luna position realative to everything else and should also give you the rate of luna repulsion away from the earth!

Go have fun!
« Last Edit: 10/05/2007 19:53:14 by jolly »

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jolly

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« Reply #26 on: 08/05/2007 13:50:04 »
Last post here in naked scientist! AS I said yesterday I cannot be bothered... to talk with the arrogant majority any longer!

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Offline Bored chemist

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« Reply #27 on: 08/05/2007 19:19:14 »
See you when you change your mind.
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jolly

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« Reply #28 on: 10/05/2007 16:42:16 »
Whatever Bored you can keep your psyco games to yourself... Just came in to add on some information to the above post... Besides I'm going traveling and not taking a lap top!... So whatever!


P.S- E=MC-B*****KS
« Last Edit: 10/05/2007 17:03:24 by jolly »

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Offline Bored chemist

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« Reply #29 on: 10/05/2007 20:14:30 »
I'm not a psychologist; my field is the physical sciences (as it happens I'm better qualified as a physicsist than as a chemist) so I will try to stick to that. I'm also not much of a games player.
Enjoy your travel.
When you get back please could you let us know what in the above post is supposed to be information as opposed to things like "Now the moon has no gravity and is pulled towards the Earth by our gravity!" which, since it's speculative at best, doesn't actually convey information. (OK that's not really physics or chemistry, but it's still an important point)

Also, there's pretty good evidence that the poles change places from time to time. While they do this there is a weakening of the Earth's magnetic field (IIRC as it happens we are in a low field era at the moment; many people theorise that the poles are about to flip). How come the moon doesn't fly away when this happens?
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Offline Batroost

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« Reply #30 on: 10/05/2007 20:35:00 »
Quote
The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth, since the amount of matter around you is no greater than the amount of matter beneath your feet when you are at the centre of the Earth.

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.


Oops. You correct in stating that there will be a point of zero-gravity at the centre - though this does of course assume a radially symmetric Earth and it isn't, quite. But as you move away from this point, in any direction, there will always be more mass in the direction of the centre than there is above you. The gravitational force always therefore acts towards the centre, never upwards.

I'm no good at diagrams but this shows you what I mean - as you (red dot) head towards the surface from the centre (green dot) there is always more mass behind you than in front so the nett force is always towards the centre.

[diagram=235_0]


 
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jolly

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« Reply #31 on: 13/05/2007 01:30:46 »
and so under that idea only in the central point would you be pulled away and you would be pulled in all directions! I dont agree with that, I think you would carry on being pulled to the core.

with regards to the moon and magnetics do we actually have any records of what happens to the moon in pole reversals, one way to check that would be to see how the tides are affected after the poles reverse, and the moon will never shoot off as the earths gravity will always hold it.

It's position will shift and change with the magnetics of the earth. I believe that- If the earth and moon had no magnetic field the moon would crash into us! It is magnetics which keeps us apart!
So if you look at the earths magnetical strength in terms of repulsion and link that to the moons magnetical strength in terms of repulsion.

Then look at the strength of the earths gravity- and calculate both these forces in equal terms- one of attraction and the other repulsion, then you would see the that the magnetic repulsive force of the earth and moon are slightly stronger than the gravitational attraction of the earth.
This would give you the distance and rate of distancing for the moon- from the earth! 
« Last Edit: 13/05/2007 15:41:41 by jolly »

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« Reply #32 on: 13/05/2007 13:48:26 »
Hang on a minute,Batroost says that "the nett force is always towards the centre."
and you say you Disagree because " I think you would carry on being pulled to the core."
That's just another way of saying the same thing.
Re "with regards to the moon and magnetics do we actually have any records of what happens to the moon in pole reversals" We have one important record; the moon is still there. If it were held in place by the earth's magnetism it would have left long ago.

"So if you look at the earths gravitational strength in terms of repulsion"
Err? as far as I'm aware gravity is always an atractive force; it's not like magnetism. There are no "like poles" that repel.
Speaking of magnetism, the magnetic effect of the moon is minute compared to its gravitational effect. So, since you say "The Tide is repelled by the moon as it passes over!" can you explain why the tiny effect of water being repelled by a magnetic force is observed but the roughly 1000 fold bigger effect of that same magnetic field on a lump of iron is not observed. It can't simply be that the sea is bigger because, while that would explain a bigger force, a lump of iron wouldn't need as big a force to move it as the sea does.
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jolly

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« Reply #33 on: 13/05/2007 15:50:17 »
Hang on a minute,Batroost says that "the nett force is always towards the centre."
and you say you Disagree because " I think you would carry on being pulled to the core."
That's just another way of saying the same thing.
Re "with regards to the moon and magnetics do we actually have any records of what happens to the moon in pole reversals" We have one important record; the moon is still there.

We have the tides!!!!!

If it were held in place by the earth's magnetism it would have left long ago.

I didnt say that magnetism held the moon, I said magnetism repelled the moon! Gravity holds the moon!

"So if you look at the earths gravitational strength in terms of repulsion"
Err? as far as I'm aware gravity is always an atractive force; it's not like magnetism.

well thanks for pointing out the typo!

There are no "like poles" that repel.
Speaking of magnetism, the magnetic effect of the moon is minute compared to its gravitational effect. So, since you say "The Tide is repelled by the moon as it passes over!" can you explain why the tiny effect of water being repelled by a magnetic force is observed but the roughly 1000 fold bigger effect of that same magnetic field on a lump of iron is not observed. It can't simply be that the sea is bigger because, while that would explain a bigger force, a lump of iron wouldn't need as big a force to move it as the sea does.

Well the sea is not just h2o... It is made up of many different particals including salt amoung others,-

I propose That probably over h2o one or a few of these particals are responisble for the magnetic repulsion of the sea by the moon! But the sea could be working in an magnetically atractive way...
And a small peice of iron is hardly a good example the sea is a huge vast body, which would feel the effects of the moon in a greater way.
It is only when magnetic force becomes stronger force than gravity that you get an effect!
Water is a polymer or has polymer qualities, how does cyfening work- It is as if the water is pulled by itself- all connected togther in a chain, provided it does'nt seperate it will pull the rest behind it!

You only get magnetic repulsion when two similer magnetic forces come into contact, If only one has a magnetic pull then you get attraction- if that force of attraction is less than the force of gravity on the object it will not move. So you need two equal or similier magnetic forces to create repulsion!

Under current scientific theory we believe that the moon was once part of the earth, I am starting to doubt that idea...

They claim currently is that the moon has an energy source that the earth does not- surely if the earth and moon were once the same body that would not be the case!

I propose that the moon was once a commit! which passed by the earth extremely closely and got pulled into our gravity, our magnetics and the moons magnetics stopped it crashing unto us and the moon has ever since been in orbit!
« Last Edit: 13/05/2007 20:12:31 by jolly »

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another_someone

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« Reply #34 on: 14/05/2007 07:26:35 »
Quote
The gravitational pull at the centre of the Earth cannot be greater than at the surface of the Earth, since the amount of matter around you is no greater than the amount of matter beneath your feet when you are at the centre of the Earth.

In fact, as Paul has suggested, at the very centre of the Earth, the gravity from all sides will cancel out, making a nett zero gravity.  Away from the centre, there will be a gravitational pull (upwards, since all the mass of the Earth is now above you), but it will only be a very slight pull, since it is still the case that most of the gravity will be cancelled out by gravitational pull elsewhere.


Oops. You correct in stating that there will be a point of zero-gravity at the centre - though this does of course assume a radially symmetric Earth and it isn't, quite. But as you move away from this point, in any direction, there will always be more mass in the direction of the centre than there is above you. The gravitational force always therefore acts towards the centre, never upwards.

I'm no good at diagrams but this shows you what I mean - as you (red dot) head towards the surface from the centre (green dot) there is always more mass behind you than in front so the nett force is always towards the centre.

[diagram=235_0]


You have to take my comment within a particular context of assuming there was a hole in the centre of the Earth where you were undertaking this experiment.

Maybe it was presumptuous of me to make that assumption, but I could not envision a way we could carry out such an experiment while embedded in a lump of rock (or even .

If one assumes one remains within this hole, then there will never be any matter beneath us, but all above us.  One only begins to have matter beneath us once we start wondering within the solid rock above the centre.

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jolly

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« Reply #35 on: 14/05/2007 14:21:07 »
this is all speculation afterall we havent been there and really dont know... these are extraplations based on what we currently believe!

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« Reply #36 on: 14/05/2007 14:47:15 »
Jolly, why do you say things like "I didnt say that magnetism held the moon, I said magnetism repelled the moon! Gravity holds the moon!" as if it's a matter of triumph for you. The thing is the moon's still up there. If magnetism held it in place it would have flown off when the field failed. If it repels then it should have fallen down when the field failed. The fact that it's still there shows that magnetism is not the force holding it in place.

"how does cyfening work"
Syphoning works because the water is always under positive pressure. That's why the "chain doesn't break" it's always being pushed not pulled.

"Well the sea is not just h2o... It is made up of many different particals including salt amoung others,-"
True but it's more than 90% water. Most of the rest is salt. Both of these are weakly repelled by a magnetic force.

"And a small peice of iron is hardly a good example the sea is a huge vast body, which would feel the effects of the moon in a greater way."
Did you not bother to read what I wrote or did you just not understand it?
A small piece of iron would not experience as big a force as a big one but (here's the bit you ignored) It doesn't need to; it's only small. A small force will affect it.
Anyway, perhaps you would be so kind as to explain why nobody notices the moon's magnetic field?
If it's big enough to give rise to the tides then it should be possible to measure the changes depending on whether it's far away or nearby.

"They claim currently is that the moon has an energy source that the earth does not- surely if the earth and moon were once the same body that would not be the case!"
Exactly who claims that?
Your logic is faulty anyway, I can take the gas tank out of a car, but I'd really like to know who you think made that claim.

As for
"I propose That probably over h2o one or a few of these particals are responisble for the magnetic repulsion of the sea by the moon! "
I propose taking Occam's razor to that idea.


Anyway, the moon is a bit of a red herring here. The question was about the earth's gravity.
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Offline Batroost

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« Reply #37 on: 14/05/2007 18:18:52 »
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You have to take my comment within a particular context of assuming there was a hole in the centre of the Earth where you were undertaking this experiment.

Understood - I was imagining something a bit different.
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jolly

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« Reply #38 on: 22/05/2007 12:15:57 »
Jolly, why do you say things like "I didnt say that magnetism held the moon, I said magnetism repelled the moon! Gravity holds the moon!" as if it's a matter of triumph for you.

Sorry bored its not a matter of triumph its actually repeating myself! and saying oh my god yet again you have not read what I posted!

The thing is the moon's still up there. If magnetism held it in place it would have flown off when the field failed. If it repels then it should have fallen down when the field failed. The fact that it's still there shows that magnetism is not the force holding it in place.

Yet again how many times, Gravity holds the moon not magnetism! Magnetism repels the moon, gravity will always hold it!
The magnetic fields repel and move the moon, they do not fail they reverse, which also will effect the moons position, and therefore the tides!


As for
"I propose That probably over h2o one or a few of these particals are responisble for the magnetic repulsion of the sea by the moon! "
I propose taking Occam's razor to that idea.

Well simple people, simple answers!!!

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« Reply #39 on: 22/05/2007 20:30:35 »
Jolly, I see you didn't take advantage of your time away to learn to read. Try reading this rather than quoting it.
"If it (magnetism) repels then it should have fallen down when the field failed. The fact that it's still there shows that magnetism is not the force holding it in place."
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jolly

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« Reply #40 on: 06/06/2007 16:58:25 »
Jolly, I see you didn't take advantage of your time away to learn to read. Try reading this rather than quoting it.
"If it (magnetism) repels then it should have fallen down when the field failed. The fact that it's still there shows that magnetism is not the force holding it in place."

Bored hello, What are talking about the field never fails it reverses, swaps around north and south change, they do not stop they change there will always be a magnetic current flowing from the earth, it may change but it never stops!

We as you point out do not know what happens to the moon in a reversal, I think the moon comes in closer then resverses as well!

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« Reply #41 on: 06/06/2007 19:13:08 »
How, exactly, does it go from one polarity to the other without going through zero?
Anyway we know it does from the geological record. We also know that the moon has stayed in the same place for a long time but that the earth's magnetic field is changing.
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jolly

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« Reply #42 on: 09/06/2007 13:53:35 »
How, exactly, does it go from one polarity to the other without going through zero?
Anyway we know it does from the geological record. We also know that the moon has stayed in the same place for a long time but that the earth's magnetic field is changing.

How is that exactly? considering that the moons is moving away from us it, and does not stay in the same place!

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Offline Bored chemist

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« Reply #43 on: 09/06/2007 16:16:55 »
OK, technically the moon's moving away, but very slowly. Stonehenge still works so the moon hasn't moved much in 4000 years. On the other hand the earth's magnetic field has changed a lot in that time.
So, the moon's orbit has stayed very nearly the same for 4000 years but the magnetic field of the earth has varied quite a bit. This proves that the magnetic field isn't what keeps the moon in place.

I see you have ignored the question about the earth's field so I will repeat it for you.
How, exactly, does it go from one polarity to the other without going through zero?

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