Is the center of the Earth hollow and at zero g's?

In a space shuttle there is very low gravity, but this does not cause solids and liquids to sublimate / evaporate. It's not like gravity holds the atoms in our bodies together, there are other molecular forces that do that.

Re: Is the center of the Earth hollow and at zero g's?

Even if, as we believe, the Earth is solid and liquid, but not hollow, the force of gravity would be zero at the center, just from the basic formula for the acceleration caused by a point mass:

g = GM/r^2

at least to the extent that the distribution of matter is spherically symmetric. Check out any high school Physics book.

Gravity at center of Earth
Yes, I wouldn't expect the matter there to sublimate but be attracted with the force of gravity outwards from the center. Maybe the center is of very low density. What forces do you think are there or maybe the pressure is at the center of the Earth with no gravity to speak of.

I am asking as I do not know the answers to my queries.
Thank you for your help.
geotom

there is no such thing as gravity, we now call it "creative falling" btw of course the earth is hollow, that's where the flying spagetti monster lives.

Re: Gravity at center of Earth

To the extent that the distribution of matter in the Earth is spherically symmetric, the gravitational force at the center is zero.

a particle in the center of the earth would have a gravitational attraction force to every other particle in the earth....but all these forces would cancel out to produce a zero net force because it has the same amount of force trying to pull it in every direciton.

There could be a spot where there is an equal attraction from mass in every direction and net force of gravity is zero, but the pressure would not be zero since every molecule would be pushed on by the weight of all the matter above it. Therefore the earth could not be hollow. Imagine taking a ball of clay and squeezing it. Even though the net force on the center molecule is zero, it still feels pressure from every direction.

If you look at gravity as a deformation of space caused by mass, there must be gravity at the center of the earth.

and seismic data indicates that there is a solid mass of stuff down there with the consistency of mayonnaise, (just very dense and hot). We know this by the waves that will and wont go through

Like a ball being squeezed
I appreciate the responses. Still scrachting!
Isn't gravity and weight related, and if there is diminishing gravity as we get closer to the center of the Earth. There would be a diminishing amount of weight over the center as we got closer. Pressure from above, to me, wouldn't add. I would think that pressure would increase to a point somewhere about half way down and then start to decrease as approaching the center.

Now that's faith.There have been pilots who have flown straight into mountains because their instruments said they were somewhere else.

Youre hitting the Whatneys Red Barrel somewhat late tonight there spendi. Im talking about seismic waves. Compressional waves (P) will pass through and bounce around via "body wave propogation, whereas Shear waves (S) and long perios (L) waves will not. Nobodys flying anything around. We set off charges in deep mines and borings and if the frequencies are low enough, like an elephants love call, we can shoot waves through theearth like ping pong balls but the S waves seem to stop at about 2900Km so thats where the liquid core begins. Theres a dense hard core beneath that at about another 1000 Km . For that we use body waves and lots of expensive equipment. Theres no chewy center or hollow core for Dinosaurs or extraterrestrials to set up housekeeping.

F = ma

weight is the FORCE that an object exerts, it is equal to the mass of an object times the acceleration of that object due to the FORCE of gravity acting upon that object...

...so how do you know the force of gravity?

F = G * M1 * M2 / r^2

The force of gravitational attraction between two objects is a constant G times the mass of object1 and the mass of object2, divided by the radius between them squared.

why is the acceleration due to gravity always -9.8 m/s^2? this isn't a constant...but there is a force between every particle on earth and every other particle. you can use superposition to treat every single particle as 1 particle in order to calculate the force that any object will have towards the center, rather than computing the force of a gazillion particles and adding them all up...

if you combine the two equations, you can cancel out mass of the first object...and you know mass of the second object can be treated as a constant on Earth because the mass of the earth is constant, and the radius of the earth is constant, so you end up getting a constant acceleration of -9.8 for any object on the surface of the earth...note that this value is going to be different if you move farther or closer from the center of the Earth

you can see by the equation that as the radius (distance from the center of the Earth) decreases (Gets closer to the center) the gravity will increase.

note: we can only treat all the particles of earth as 1 giant particle if we are OUTSIDE of the radius of earth

when you are at the center of the Earth, the radius=0...you obviously can't divide by zero. but you dont need to, because you can realize that you have an equal number of particles all around pulling in all directions, and their force will cancel out...which is why the particle in the center doesn't move out from the center (well volcanos are a different story )

PRESSURE is just a measure of how much force is acting on an object, unlike gravity it does not cancel out if you have a force from two opposing directions, it adds. since we already established that particles CLOSE to the center have the strongest gravitational force towards the center, we know that the particle at the very center has all the strongest forces pushing against it from all sides.

so, pressure can only increase as you travel inside the earth towards the center. just like being under water, the more water you have pushing down on top of you, the more pressure you have...imagine a millions of tons of rock "falling" on you from all directions, yeah the pressure at the center is going to be high...

gravity is a different story...once we penetrate the surface of the Earth, you can no longer treat all the particles as a single particle, im not going to try to explain the math to you but if you just think about it...it's going to be decreasing as you get closer and closer to the center because you have rock at the surface trying to pull you back from the center. finally at the very center, it's pulling from all directions equally so you won't be moving...that means net force = 0

Yesss

Been Dere.
Done Dat.
Fell off the bar stool at Symmes Hole.
And yes I started to float as I approached the floor.

Rap

If it was completely hollow it would cave in on itself right? I believe it has solids areas with many caves, and areas that sustain some life forms.

Re: Like a ball being squeezed


The pressure does add. If pressure was to be canceled out by gravity there would have to be a gravitational pull away from the center of the earth at some point. A mere lack of gravitational pull only keeps more pressure from being added.

Think of a pressure tank. There isn't much gravity pulling the contents at the center towards the center, but pressure at the center is still as high as at the edges. If gravity was to cancel it out, it would have to pull away from the center towards the walls of the pressure tank.

If you could determine density multiplied by gravity as a function of the distance from the center, you could calculate it. Integrate f(r) from 0 to well into space, and you'd get the pressure at the center.

Incorrect. The vector sum field is zero.

Re: Like a ball being squeezed

Pressure and weight are different things.

Gravity at center of Earth
Thanks, I'm beginning to get the picture maybe??

Let me get this on the table to help me understand.

If a cubic centimeter of say iron weighs about 8 grams at the surface of the Earth, and there is no gravity at the center of the Earth, then the weight of a cc of iron would be zero at the center. Without integrating over the total distance from the center of the Earth to a spot somewhere in space- What would be the weight of the same cc of iron say at 100 meters from the center of the Earth. I would suspect it would be far less than 8 grams.

If the pressure of a column of iron out to that point in space is the summation of each cc of iron, my thinking would be, the contribution of the cc at 100 meters would be a much smaller contribution to the total pressure of the column.
If I'm thinking straight (probably not) this would again lead me to believe the iron around the center of the Earth is less dense. Help??