What happen to gravity in the center of earth

[jsm6252]

if the center of the Earth was hollow would you float around like you were in space.

 

[mathman]

Assuming the Earth is spherically symmetric, yes.

 

[vardhan_harsh]

Yes,as in case of a spherically symmetrical earth,the force at the centre will be neutralized as it is acting from all directions.

 

[Nik_2213]

Don't forget the Moon's gravity will offset the sweet-spot...

 

[ttmark]

You will experience the lack of gravity effect but you will still be rotating about the earth/moon system center of mass.

 

[Wonderbread]

you change the position of the center of gravity if the Earth center was a hollow sphere, the the gravitational center would be around the edge of the spere equal in all directions,

 

[DaveC426913]

Don't forget the Moon's gravity will offset the sweet-spot...

No.

1] There is no sweet spot. Or more accurately, everywhere is sweet. In a hollow spherical shell, gravity everywhere inside is zero.

2] The Moon's gravity is already taken into account. The Earth rotates about the Earth-Moon barycenter, as does any floating person. So the person's motion - relative to the Earth - will be zero.

 

[Wonderbread]

your body would occilate from the edge of the sphere back to the surface and back down to the edge of the hollow sphere til teminal velocoty was reduced to zero if you fell inward otward the center of the hollow shere

 

[DaveC426913]

you change the position of the center of gravity if the Earth center was a hollow sphere, the the gravitational center would be around the edge of the spere equal in all directions,

How can a centre be around the edge of something?

Again, the gravitational force experienced anywhere inside the hollow shell will be zero.

 

[Wonderbread]

The traveler accelerates toward the center of the Earth and is momentarily weightless when passing through the geometric center at about 7900 m/s or almost 17,700 miles/hr. The traveler would pop up on the opposite side of the Earth after a little more than 42 minutes. But unless he or she grabs something to hold on, they will fall back for a return journey and continue to oscillate with a round-trip time of 84.5 minutes.

 

[Wonderbread]

How can a centre be around the edge of something


in a toroidal core

 

[Wonderbread]

or a manifold

 

[DaveC426913]

The traveler accelerates toward the center of the Earth and is momentarily weightless when passing through the geometric center at about 7900 m/s or almost 17,700 miles/hr. The traveler would pop up on the opposite side of the Earth after a little more than 42 minutes. But unless he or she grabs something to hold on, they will fall back for a return journey and continue to oscillate with a round-trip time of 84.5 minutes.

Yes and no. This would be true if the hole were of neglible volume/mass compared to the volume/mass of the Earth such that you were still accelerating all the way to the centre.

But the OP said "hollow". This means the open area inside the Earth is quite signifcant compared to the volume/mass of the Earth.

If a traveler fell off a cliff toward the centre, they would accelerate (though it would be much less than 9.8m/s^2 because the Earth, being hollow, has much less mass), but they would only accelerate until they reached the inner edge. Once they reach the inner edge, there is no more gratitational force to accelerate them, and they would drift at constant speed until they reached the far inner wall, at which point they would begin declerating.

So, they would oscillate, but it would take a muuuuch longer time than you claim. (Initial acceleration is much slower, and only lasts a short time; bulk of journey is coasting.)