Would gravity affect us differently if we were in the center of the earth.

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    Center Earth Gravity
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Discussion Overview

The discussion revolves around the effects of gravity on a person located at the center of the Earth, exploring theoretical implications and assumptions about Earth's shape and density. Participants consider various models of Earth's structure and how these might influence gravitational experiences.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that if the Earth were perfectly spherical and uniform, gravity would be zero at the center due to symmetrical cancellation of gravitational forces.
  • Others argue that the Earth does not need to be perfectly spherical; as long as it is smooth and symmetrical, gravity from opposing sides would cancel out, resulting in no gravitational pull at the center.
  • One participant notes that even with symmetry, the density must also be symmetrical for the cancellation of gravity to hold true.
  • Another participant suggests that irregular shapes and density distributions could still lead to a center of mass that allows for gravitational cancellation.
  • A later reply summarizes that at the center of the Earth, one would experience no net gravitational pull, leading to a sensation of weightlessness, while still being influenced by external gravitational fields, such as those from the moon and sun.
  • Concerns are raised about the effects of atmospheric mass on gravitational experiences just above the troposphere, indicating that local variations in mass can affect gravity.
  • Some participants emphasize that despite the lack of net gravitational pull, one would still experience effects such as time dilation due to being surrounded by mass.
  • There is a mention of the impracticality of surviving at the center of the Earth due to extreme conditions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the assumptions regarding Earth's shape and density, and multiple competing views regarding gravitational effects at the center remain present throughout the discussion.

Contextual Notes

Limitations include assumptions about Earth's shape and density, as well as the implications of external gravitational influences, which are not fully resolved in the discussion.

AgentPancake
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i think it should but I am not sure.
 
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AgentPancake said:
i think it should but I am not sure.
If we assume that the Earth is perfectly spherical and uniform (which it isn't really), then we would experience no gravity at the centre of the earth.
 
I don't think we need to assume the Earth to be spherical; for as long as it is smooth and symmetrical...you know, it could still be a bit flatten at the poles and wider at the equator...but for as long as it is symmetrical then gravity from one side cancels gravity from the diametrically opposed side, etc. and so, if you were at the center of an Earth like this, you would experience no gravity from earth...but you will still be subjected to gravity from other bodies (moon, sun).
 
You've got to be right in the middle though.


An interesting, although not completely related case is that of people actually being on Earth. The atmosphere has mass, and it's not completely negligible...so the gravity just above the troposphere is slightly more than you'd expect. And all because you have to take into account more mass...
 
gsal said:
I don't think we need to assume the Earth to be spherical; for as long as it is smooth and symmetrical...you know, it could still be a bit flatten at the poles and wider at the equator...but for as long as it is symmetrical then gravity from one side cancels gravity from the diametrically opposed side, etc. and so, if you were at the center of an Earth like this, you would experience no gravity from earth...but you will still be subjected to gravity from other bodies (moon, sun).

It must have symmetry but also must have symmetrical density
 
It doesn't need to be perfectly symmetrical however. The gravitational pull of one tonne, or 10^5 tonnes or any other relatively small amount (we're talking gravity here, the weakest of the forces) won't have a huge difference.
 
Oh yeah, in fact, it doesn't need to be regular at all and it doesn't need to have uniform density.

A slightly irregular shape can have an irregular distribution of density and still have C.O.M. in its "centre"
 
There was a pretty long and complicated thread a few months back about this. It boils down to this: At the center of the Earth you have no NET pull in any direction. The force of gravity of all that mass surrounding you cancels out in every direction. In effect you should feel like you are weightless. However, you are still under the influence of a gravitational field and would experience all the normal effects such as time dilation and such just like you do here on the surface, but at a slightly greater effect due to being in the middle of the mass instead of just on one side. Of course you would never survive being in the center of the Earth without being crushed...
 

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