Where is Earth's gravity stongest?

I was asked where the Earth's gravity was strongest earlier, and I have no idea. It's actually a very complex question. The question asked whether it was on or in the Earth...

I suspect it's several thousand miles under the surface because the core is much denser, but I'm not sure! I can picture a graph which slopes up and you go under for a while, then slopes back down to zero at the centre.

Does anyone know the answer?

Gravity is the strongest where ever the fattest person on earth curently resides.

Or it could just have equal gavitational forces disperced equally over the northern and southern hemispheres of the earth....

I'll tag for later. I think we know too little about gravity. I've seen discussion though that as you near the core the gravity approaches 0.

well the wiki on gravity here should cover most questions

reply to post by BagBing

Not sure of where it is heaviest, here are some variables to consider:

1. latitude (gravity increases toward the poles)
2. posiiton of the moon
3. topography (gravity decreases with elevation, and varies according to surface shape)
4. density of underlying rocks
5. type and amount of overburden

A European spacecraft that skims the upper reaches of the atmosphere has mapped Earth's gravity with unrivalled precision. The map shows how the pull of gravity varies minutely over the surface of the Earth, from deep ocean trenches to majestic mountain ranges.

The measurements have allowed scientists to create a computer model called a geoid that reveals what Earth would look like if its shape were altered to make gravity equal at every point on the surface.

Researchers unveiled the latest data from the European Space Agency's Gravity and Ocean Circulation Explorer, or Goce, at a workshop in Munich on Thursday. The map shows areas of strongest gravity in yellow and weakest in blue.

www.guardian.co.uk...

There are places called vortexes too, where gravity is supposedly heavier, but I think that is still speculative.

reply to post by BagBing


I am just guessing, but it seems to me that would be in Africa, somewhere south of Egypt where the Nile River begins since it flows north instead of south.

Dunno...just a guess, nice OP though

Gravity as in why the apple falls to the ground is do to the differential in mass of the apple compared to the the atmosphere that surrounds it.

A apple will fall faster where the atmosphere pressure is less compressed. The higher up you go into our atmosphere the faster the apple will accelerate if you drop it.

Right under my butt. I know this is fact because the pull to stay sitting is overwhelming.

My UNeducated guess would be at the poles or along the equator.

Am I right?

I would have to say the lowest point on the planet. It makes sense that the gravity is weaker the higher you go, so it would be stronger the lower you go.

Just my guess though.

reply to post by BagBing


The strongest place of gravity would be inside earth, at it's gravity center. It's that point that attracts you to the floor... It's located somewhere near the center of earth, not necessarely exactly at the center, but not far.

If you approximate the earth as a uniform sphere, gravity will be strongest on the surface, and will decrease as you drill down (think of it at the extreme of drilling - at the centre - you will be pulled in all directions around you, meaning the force is exactly 0 and you are weightless)

It's relatively equal but and hardly discernible but...technically the strongest gravity would occur at...
The Equator....and why the oceans actually bulge out slightly there contributing to the oval/oblong shape of the planet earth at the equator.

Peace

reply to post by BagBing


Gravity is felt to be strongest at the poles. Any closer to the equator and the Earth's rotation begins to counteract it.
However, disregarding rotation, gravity is strongest at the surface. It decreases with the square of altitude, and it decreases linearly with depth, becoming zero at the center.

Thanks for the replies!

Gravity at the dead centre of the Earth would be zero, and gravity on the surface would be strongest at the poles because:

a) they're closer to the centre,
b) the Earth's rotation (centrifugal forces) would "oppose" gravity at the equator.

Don't forget that the Earth is not spherical or uniform in density.

bermuda triangle?or that place in some dessert where thing get pulled/drop from the sky cant think where it at though

reply to post by CLPrime


Cheers, but I'm not so sure about that. There's effectively a bloody great iron ball in the middle, which contributes to a significant portion of the Earth's mass. That's why I suspect it's under the poles...

reply to post by CLPrime

You beat me to it CLPrime!

I was going to post that the question needs to be defined better. Is the OP asking where is gravity the strongest, or where does the net effect of gravity FEEL the strongest. As you correctly pointed out, the rotation of the Earth does have an effect at the equator.

Either question is indeed somewhat complex to answer.

NASA's website gives this information which I suspect doesn't include the effect of the Earth's rotation:

www.jpl.nasa.gov...

There's big gravity low off the coast of India, where there are thought to be the remains of some old mantle features associated with the plate tectonics of India that led it to collide with the Himalayas. There's a big high in the South Pacific, also thought to be due to mantle structures.

Regarding whether gravity could be higher below the surface...I doubt it, because as soon as you go below the surface, the mass above you exerts a gravitational pull in the opposing direction. so it would be impossible for gravity to increase if the composition was homogeneous, but as the OP points out, it's not homogeneous and denser materials are at the core. Still, I think the inhomogeneity isn't sufficient to offset the pull of the gravity above once you go below the surface, though I suppose it's possible there might be a rare exception somewhere if the density gradient is large enough.

Think of it this way, if you could travel to the center of the Earth, it would be pulling on you more or less equally from all sides, sort of "zeroG" effect. So if you can picture this, you can understand why going below the surface probably doesn't increase net gravity but lowers it.

reply to post by BagBing


It doesn't matter. Gravity begins to decrease as soon as you start going underground. The only thing that would change that even a little bit is if the core was significantly off-center. Which it's not.

reply to post by CLPrime


This answer seems to me to make the most sense, however there are obvious anomalies according to the Geoid produced by the ESA in the video posted above. This question is a very tricky one for us and I don't believe that even the best scientists in the field truly know the answer.

It might be best to start with a theoretical planet that has no variances in its composition and work from there. After we have a decent model, we can start to add features that our Earth has and try to see how they would affect gravity.

S&F to the OP for making us think!