So I was in the shower today...

[Agamemnus]

But remember how massive they are? Each of their gravity would be equivAlEnt to something around 4.4m/s^2. So now you have a force of (4.4m/s^2)*(half the mass of the earth) pushing on you from both sides. You'd be crushed. You're thinking that somehow you'd be safe in the middle because there is no gravity. But there is gravity, you're just cancelled out from the equivAlEnt mass on both sides. The 2 masses still want to come together whether you're in the middle or not, and their gravitational force will make it so. Then once they collide and become 1 object, gravity will not stop there. It will still cause a force for everything to push towards the center of gravity.

>So now you have a force of (4.4m/s^2)*(half the mass of the earth) pushing on you from both sides.

You can't just divide the mass of the Earth by two and say the gravitational force on the surface is also halved. Also, m^2/s^2 is not force, it's force times mass.

>thinking that somehow you'd be safe in the middle because there is no gravity. But there is gravity, you're just cancelled out from the (equivAlEnt) mass on both sides.

I didn't say there wasn't gravity. People can't be cancelled out.

>The 2 masses still want to come together whether you're in the middle or not, and their gravitational force will make it so.

So?

>It will still cause a force for everything to push towards the center of gravity

So? The force will be small at the center because gravity will be low. Just because everything forces towards everything "below" it doesn't mean that you can somehow add up the forces. You're going to lose a lot of that force from simply the density of matter that stops the force, from magnetism, and also from the much smaller force in the center and near the center.

[Radical Raccoon]

>So now you have a force of (4.4m/s^2)*(half the mass of the earth) pushing on you from both sides.

You can't just divide the mass of the Earth by two and say the gravitational force on the surface is also halved. Also, m^2/s^2 is not force, it's force times mass.

It's the concept that matters here and not precise calculations.

>thinking that somehow you'd be safe in the middle because there is no gravity. But there is gravity, you're just cancelled out from the (equivAlEnt) mass on both sides.

I didn't say there wasn't gravity. People can't be cancelled out.

Yes they can. Ever played tug-o-war? If both people are pulling equally on both sides then no one's going to move and no one's going to win. Now imagine that you hang a ball at the center of this rope. If you grab one end of the rope while someone else grabs the other, then you both pull in opposite directions with equal strength what happens? The ball doesn't move, not because there is little or no force, but because the forces have cancelled each other out.

So? The force will be small at the center because gravity will be low. Just because everything forces towards everything "below" it doesn't mean that you can somehow add up the forces. You're going to lose a lot of that force from simply the density of matter that stops the force, from magnetism, and also from the much smaller force in the center and near the center.

Gravity is not low at the center. You're not speaking in the right context. It is a common misconception that there is little to no gravity at the center. Though, it is correct that if the center was hollow and you were placed in the center that you wouldn't be effected by the gravity of the surrounding mass. But this doesn't mean that there is little gravity at the center. You'd still have a pull to one side, but the opposite side is also pulling on you just as much; that's why you wouldn't move, not because there is "low" gravity.

Pressure at the center can better be described in terms of vectors. Indeed you do add up the forces. If you don't believe so then you need to learn about the concept of vectors and how they can be applied. Then you'll have a better understanding of this subject and physics in general.

[Zack]

It's like being in orbit. You feel weightless but in fact you are still under the force of gravity.

[NecrosIhsan]

And you guys all have firsthand experience in all this stuff you're blabbering on about...right? Right? :laughing: :laughing: :laughing:

[Agamemnus]

And you guys all have firsthand experience in all this stuff you're blabbering on about...right? Right? :laughing: :laughing: :laughing:

hifty:

It's all mostly maths not conjecture.

You'd still have a pull to one side, but the opposite side is also pulling on you just as much; that's why you wouldn't move, not because there is "low" gravity.

What's your point? You're just proving what I've been saying. The effect of the forces cancelling out is low gravity.

Pressure at the center can better be described in terms of vectors. Indeed you do add up the forces. If you don't believe so then you need to learn about the concept of vectors and how they can be applied. Then you'll have a better understanding of this subject and physics in general.

You don't add up the forces because of the reasons I mentioned and I'll mention some more, too: friction, the permeability of matter, magnetism. If you hit a ball with force X, which is moving at force Y, and that ball hits you afterwards, the total force is not force X + force Y. Don't lecture me about learning concepts either.


...

[Zack]

And you guys all have firsthand experience in all this stuff you're blabbering on about...right? Right? :laughing: :laughing: :laughing:

Depends what you call first-hand...I don't think anybody has physically been exactly halfway between two objects exactly half the mass of the Earth, but I've certainly read and been taught about everything I've discussed in this thread. In fact, I'm leaving in 15 minutes for my three-hour physics lecture at the University of Toronto, and last term I went to two lectures a week in second-year general astronomy.
You seem to really like killing discussions on the basis that nobody has the right to discuss anything.

[aetherfox]

Zack, you ignored what I said before - I was talking about the formula applied as a limit. Division by zero in a limit yields infinity.

[Agamemnus]

Yes, it does. . . .

[Polter]

Hey people, you're just talking about Newtons definiftion of gravity, the attraction of objects in space right?
Correct me if i'm wrong...

But look at einstein's side?
Gravity is far more vast than the so called "attaction"...
It is like the property of matter in space...

Space without matter is like space without gravity, and if you placed a matter in space, gravity would occur.
The matter will cause distortion on space, say for an example, a cannonball on a taut sheet of canvas.. the cannonball would make a dimple on the canvas, thus, if you roll another ball, the ball will "come near" to the other cannonball because of dimpling on the canvas...
so to say it in 2-d in the canvas, and 3-d in the space...

[SJ Zero]

Zack: In calculus, we use 1/0 = infinity all the time. It's one of the fundamental axioms which allow us to determine the limit of an equation.

Agamemnus: Gravity on any certain point will be equal to the summation of the product of each mass surrounding it divided by R^2, with a scaling factor thrown in there. This does mean that if you approximate the earth as a solid ball of matter, as you get further down into the earths crust, gravity will "reduce" because the opposing mass at the other side of the earth will decrease the effective gravity.

However, this isn't the end of the story. The force applied upon the center of the earth is equal to the sum of the force exerted upon the earth by the entire mass still affected by gravity. You can argue that the ground isn't affected by gravity, and I can then empirically prove you wrong by throwing dirt at you. The sum of all the force applied by all the different layers of the earth, with all their different gravitational constants, is then multiplied by the area of the core. With that completed, you'll immediately see that there are massive pressures at the center of the earth. Those pressures increase the melting temperature of any substances unlucky enough to be that far down, resulting in a solid core surrounded by superheated magma. As an aside, the high energy at the core MAY result in a point gravitational field because the amount of energy would raise the relativistic mass.

And if you don't understand, I recommend taking a physics class or at least reading a book. Glenn isn't the only person around here with university-level physics under his belt, and watching your weekend warrior attempts against people who are also applied or theoretical physicists is painful.