If we compare it to a rope pulled by two equal forces in each end. The net forces would be zero and you would have static equilibrium, but the rope would still break if pulled hard enough.
Additionally, wouldn’t a metal ball uniformly surrounded by powerful magnets be pulled apart as well?
I am not sure why I can’t wrap my head around this, when it comes to the center of the earth.
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The big difference is easier to understand if you simplify a little. Tension happens when two *different parts* of something are being pulled in different net directions. If we imagine only one “part” (eg, atom) of the body, its net force is zero. The part next to it also has a net force of zero. They agree on which direction to move (nowhere) and thus don’t pull against each other and experience tension.
If you are in the center of a hollow sphere, the gravitational force will pull you towards the center, not out towards the shell. So if you turned up the mass of the shell, it would crush you instead.
Just think of what it would mean if there was a pull outwards. It would be impossible to even stay in the center because the smallest change in position would increase the force pulling you away from the center, which further accelerates you away from the center.
There would be a slight gradient as a body isn’t a point, and as gravity increased you’d eventually be ripped apart. But i guess the planet would collapse into a black hole first.
To add on to the excellent answers here already and hopefully illuminate a little more on the subject, gravity is fundamentally caused by invisible foot goblins tugging on your gams.
Since they live just below the surface and nowhere near the core, you’ll just float about freely if you ever find yourself there.
the pull from inverse square force is zero inside hollow sphere at every point ( not just the centre). this is as a result of calculation. it is same for electric forces
Another important aspect that sets gravity apart is that gravity is a *body force*, which means that it acts everywhere, including the inside of objects (their “bodies”). That’s different from other forces that act only on the surface (like pressure from a fluid) or on points of contact (like the ropes pulling your arms apart).
In a uniform gravity field (the Earth’s surface is a good approximation for us) the force of gravity pulls on every atom in your body with the same force (or, rather, acceleration), so there’s no tension between any internal part. A rope tied to your hand, on the other hand, is only pulling on your hand, not on the rest of your arm or body, which is why it hurts.
If you were floating in space, and a uniform gravitational field suddenly appeared, you wouldn’t feel anything, *no matter the strength of the field*, because every atom in your body would be pulled with the same acceleration. You would actually feel just as weightless as when you were floating in free space. That’s what body forces do.
Real gravitational fields from finite objects aren’t exactly uniform, of course, so other effects, like tidal force (atoms in your body a little closer to the source are pulled a little more strongly), become relevant. But these are second-order effects.
The gravity from the northern hemisphere of the earth would be pulling on your feet as much as the southern hemisphere will be pulling on your head but also vice versa. If your feet are being pulled strongly to the south pole they’ll also have a force pulling them to the north pole.
Imagine being in water. You don’t feel the weight of the water on top of you because the pressure from the water below you cancels it out.
I think the mistake you are making op is thinking of gravity as a force. Which it isn’t. its not like invisible tethers pulling on you.
If you think of it like a spacetime curvature instead it makes more sense how gravity can cancel itself out if you are in the center of a big hollow object. Its not like in a material we pull on where we have stress on all atoms.
But rather its like being on a big trampoline with a big weight around you(like a cylinder with you standing within the cylinder), the trampoline floor tilt in this example will be the gravity (spacetime) effect. Within this big cylinder the floor will be very flat, thus you wouldn’t be “falling” towards anything, just standing there normally, unaffected by the floortilt.
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