Thinking outside the box - Gravity problem

Greetings, Now I did physics up to an A Level standard and thus understand physics to a good level. What I am looking for is for someone to explain this problem I thought up the other day because it is beyond me!

Let us asume I drill a Hole through the earth from the north pole to the south. Thus my tunnle goes right through the center of the earth. I now stand at the North Pole and jump down this hole. Now asuming there are no considerations for heat i.e. the earths core. What would happen to me?

I look forward to your replies!

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You would fall to the center of the Earth.
Then inertia would carry you past the center and as far against the pull the center of the Earth as it could and then you would fall back to the center again. [Providing you didn't get shreaded/burned-up scraping the sides of the tunnel at a high velocity.
You would oscillate back and forth, i believe, in ever shorter movements until you after a very long period came to rest floating at the center of the Earth.

Lots of pressure, zero gravity.
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Thanks for the quick reply slank!

Yeah I figured it would be something like this. So have I discovered an way of achieving a complete loss in mass i.e. anti gravity/gravity shielding? Or can it be considered as such, been as how mass is effected by gravity, thus my mass is effected by the earths mass when I am on the surface and when I am underground at the center point the earths mass is not acting upon me?

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The Mass of the Earth is still acting on you, but it pulls on you equally in all directions at the center and therefore cancels itself out.

I was thinking if you graphed the gravity function of the Earth It would peak at its surface and get flatter and flatter down to zero at its center. Which to me seems almost counter intuitive based on experience.

Also that means the warp of the Universe may come up in the middle of a gravitational body like Earth, Which is definitely counter intuitive. Unlike the Ball analogy that is often used the actual shape of of the Universe at a gravity body is a cumulation of many little spikes down at each nucleous and electron that actually peaks at the surface of a body and then rises up to vitually nothing at its center.

The Gravity field of the Earth [or other heavenly bodies] is not a 'U' shape but a 'W' shape [roughly speaking].

Anyone have any rational arguments that counter this idea?
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I probably do not know as much about physics as you, but still I find the relationships between mass and gravity interesting. Just like the above posters, you would accelerate to the center and then back and forth until you reached a state of equilibrium.

The thing is, mass in and of itself is a product of gravitational force. Without gravity, there would be no mass.

What produces gravity? I believe the key to unlocking antigravity is the fact that any time a mass is in motion - specifically rotating - it produces a pull towards its center. Think of it as a reverse of centrifical force. The earth has a mass and rotates and therefore produces a pull. The moon does the same, but since its mass is less and its rotation is less, we have less gravity.

Thinking about countering gravity, maybe we should think of ways to develop rotating masses that are matched to counter the earth based on its mass and relative speed.

I really think the equation would be as simple as earth mass/rotational angular velocity=local mass/local angular velocity. Maybe I am wrong.


EDIT: maybe we could think about this. I am sure the mass of the Earth is known and so is its velocity. Say we had one spinning mass or an array, what speed and mass would it take to duplicate what the Earth does and do you think if we stood near it, it would draw gravity towards it?


[edit on 1-8-2005 by ben91069]

Only if he made a near perfect vacuum in the tunnel. If he would not do that, he would stop pretty much in the middle. Under atmospheric conditions, due to air friction terminal velocity is reached at somewhere around 250 km/h (I don't know the exact figure, you can look it up) depending on whether you go down with your head down, arms next to your body or legs and arms spread out and body perpendicular to direction of the fall. If the tunnel would go all the way to the center of the earth and is in connection with the atmosphere, the air pressure would increase towards the center, just as the pressure in the ocean increases with depth. Hence also your terminal velocity would decrease several times towards a pretty low speed. Since air is almost one thousand times lighter than water, the increase in pressure would not be as dramatic as in the ocean but would still be enormous when getting near the center. The air pressure hence could be lethal from a certain point on. Your terminal velocity would further decrease as the force pulling you towards the center becomes ever smaller only to come to zero when reaching the actual center. So your dead body would be moving at a very slow speed when reaching the actual center and wouldn't go up again but for at best perhaps a centimeter, where it would remain to float and decompose in zero G conditions.

[edit on 1-8-2005 by Simon666]

I haven't read the rest of this thread, so pardon me if I repeat some one. You would fall through the hole all the way to the other side but slightly lower elevation than you started, then you head back the other way again ending back up at the north pole at a lower elevation than you had been at the south pole. You would continue the decreasing oscillation back and forth through the tunnel, each time having your "peaks" closer and closer to the center, until finally you would end at the center of the earth - weightless, hovering there until we came and got you and threw you in jail for destruction of public property.

Ben: There is no such thing as centrifical force (I don't even think I can spell it). There is centripetal force, which is an acceleration inwards when you're circling around something. It can be a satellite orbiting or a weight on a rope. It doesn't have to have anything to do with gravity at all. Centripetal acceleration is the velocity of the object, squared, divided by the radius of it's orbit.

That's assuming you didn't melt first. It gets awfully hot after the first 100 miles.

lol, yes I would serve a hell of a lot of time for that one! Thanks for your answers guys. You've been very helpfull in solving that one for me

Forgive my physics ignorance. Maybe I am not really saying what I mean here. It seems possible, that there is some force that flows through the atomic structure of things. When they are stationary, not much happens. When they rotate, it seems they twist this force into a central point, just like the earth. Perhaps this force makes the matter rotate, but just like vibration makes sound waves, we can make sound waves vibrate an object.

Hopefully my physics ignorance doesn't keep you from seeing what I am trying to say here.

I think, some force permeates the galaxy. Because it is a spinning mass, these lines of force somehow create gravity both on a large scale and locally - like the earth or the moon.

I think the idea of gravity is very similar to electromagnetism, although they are not the same, but don't you think at least the formulas for how electomagnetic flux is quite similar to the key to how rotating masses create gravity towards there center?

Edit:
Let me add an additional note here. The moon - because of it's distance and mass from earth and the sun has a certain gravity. There is probably some equilibrium here, or it would fly off into space or get pulled into earth. Nevertheless, suppose we created a ball of lead with the same mass and spun it around the earth at a faster rotation?? It would eventually find a new orbit around the earth because of its rotation, orbit, mass, whatnot. So, if created a very small ball of lead and positioned it a mile from the earth and rotated it at some astronomical speed, then perhaps we could achieve a zero gravity point between the earth and this object??

[edit on 4-8-2005 by ben91069]

mass is the amount off a substance
gravity is a product of mass
more mass, means an object has more gravity
weight is the force of gravity pulling
at the center of the earth, i still have mass of 80 kgs, but my weight is 0 because the force is pulling in all directions equally

on the moon i weigh 25 kgs or something, however my mass is still 80 kgs
mass is measured by how many kilograms an object weighs when a gravitaional force of about 9.81 metres/second^2 is applied.
weight is the mass multiplied by the local gravity, and is correctly measure in newtons.
ie mass is 80 kgs, weight at g=5 m/s^2 is 400 newtons

I think Simon666 is on the right track. If you ever made it to the center of the Earth at all, you wouldn't go far beyond that, but would hang in weightlessness forever at the center ...

Any evidence to this?



Do you mean circular motion/centripetal forces and accelerations? Because I don't see anything wrong with that.



Spinning objects of mass "drag" spacetime along with them, thus creating gravity occurences not necessarily predicted.



If it were this easy, someone would've found the GUT already. They were, at one point in time, one, single force, but have since split up and are thus far irreconcilible. (If only because Gravity likes Relativity and everything else likes QM, and Relativity and QM don't like each other)



Yes, you could, but it'd be at the center of the ball for all intents and purposes.

Damn!! That is an interesting post Simon666 until I read it I would have been prepared to believe the back and forth theory.

If I get your meaning correctly, it would be like firing a bullet into water. The density of the water would absorb all of the bullet's energy and it would come to a complete stop. (A bullet fired into water actually does come to a complete stop for an instant then gravity takes over and it sinks to the bottom.)
In this case the increased air pressure would mean that the air is more dense the closer you get to the core and terminal velocity would be greatly reduced.

There is something to do if we can ever get a long drill to an asteroid.

I too have wondered similarly about this: www.abovetopsecret.com...

There is no definant way to tell for certain what will happen, yet. Though, looking at an atomic scale we see that certain elements are able to absorb neutrons and under a different isotope split in half when having a neutron fired at it. So I don't think using any theories on an atomic level are feasible in this arguement, yet.

Anyone ever tell you that you're weird, Frosty?

My feeling is that it's probably safe to say that this velocity of 250 km/h would be reached.



This part ain't necessarily true. It is erroneous to assume that the air pressure would increase in a manner similar to the way water pressure increases in the ocean depths. After all, the ocean is on the Earth's surface, the hole is not. As anything (air or a person) flows farther into the depths of the hole, more and more of the Earth's mass is exerting an upward force. Hence, at the center, the air pressure would be zero.
The variation of air resistance against the acceleration of a falling body versus distance into the hole makes for an interesting differential equation.



Your terminal velocity would certainly not decrease due to this. F=Ma remember. Any "F" will result in an "a."

Also, this is precisely why the air pressure would decrease. Remember though, with less air pressure, you may be allowed a higher terminal velocity than the before mentioned 250 km/hr. It's worth repeating here that, although it's true that the force pulling you down would decrease with distance into the hole, that force would still be operating and would still result in acceleration, albeit a decreasing acceleration. Another interesting differential equation.



The only real difference between gravity and electromagnetism is that there is a positive and negative side to electromagnetism. That and the vast differences in force strength. This lends no validity to your theory about a rotating Earth "creating" gravity though. Rotating currents do not "create" electromagnetism either. They merely arrange existing EM fields in a manner that results in a single (looking) strong field.

If you take a coil of wire and run current through it, a magnetic field appears with the north pole of the field at the end of the coil found using the right hand rule. The south pole is at the other end of the coil. A ferromagnetic object placed loosely in the coil could be accelerated out of the coil by the magnetic force, assuming the current was high enough and the object's mass was small enough.

If you take a coil of extremely durable tubing and somehow pump extremely dense matter through it, a gravitational field appears with the direction of force at the end of the coil where the matter flows out. Note that the "right hand rule" doesn't apply, a consequence of gravity (unlike electromagnetism) not having positive and negative associated quantities. An object with mass placed loosely in the coil could be accelerated away from the coil, assuming the rate of flow (and density) of the "pumped" matter was high enough, and that the object in the coil had small enough mass.

The similarity here is that you are "pumping" the particles that have the necessary associated force (electrons - electromagnetism, particles with mass - gravity).

Harte

That question was asked, and answered back on November 30, 1979.

Cecil Adams knows all

I think you'd find disscutions on the Aether fit this idea of yours quite well. The Aether is said to permeate all of space and is fluidic in nature. As you say, the spinning bodies create flow in this Aether which is what we percieve as gravity. ( Magnetism is also said to be produced by this flow of ether but rather a directed flow trough an obect due to the oreintation of its particles ).

Oh and as to the actual topic question I have to agree that assuming air fills this hole then air pressure would increase towards the center of the planet. This would likely cause a rapid deceleration towards the center of the planet as stated in earlier posts. However, I feel you would need to draw up some proper diagrams and do some calculations to know for sure. Over shooting the center is quite likely then oscillating back and forth until the center is reached.