If i was to drill a straight hole deep through the earths crust from the north pole up to the south pole and jumped in.. How would i fall out from the south pole ? would gravity slow me down as i reached the other end ??
Good question. While I don't know for sure, I would think that gravity would stop you right in the earth's core. It seems that since gravity is pulling all objects on earth downward that you would have to stop in the core since that is as far down as you could go. Any farther and you'd be falling up (back toward the surface).
The same question was suggest once on the television, of course they had fun with a graphical detail of a person appearing at the other end of the earth for a moment, then falling back through the hole again. However the reality might actually be a little different. Gravity is suggested to be waveformations made up from particle movements in atoms, the particles movement suggestibly alters the surrounding spacetime like a ripple effect coming out from a droplet on a puddle. It's suggested that the closer you are to the gravity source the greater the ripples effect and the further away the more dispated it is. This means that the gravity of the earth is made up of all the atoms that are trapped within it's atmosphere, with solid mass generating a greater gravity. This then gives way to a theory originally that the poles were only existant because of the molten core "swirling" due to the earths spin, However it's suggested that when the rock cools it generates a "Permanent" position (This is notible with Magnetite and the generation of "Permanent Magnets") In turn it suggests that if the core generates a moving magnetic field and the Crust/Mantle contain a permanent field either the core would stay stable within the centre of the earth or the crust/Mantle would occasionally move because of the altered magnetic state which can explain some Tectonic movements. (Most Tectonic movements though are caused by magma flow being redirected) [Thanks Adam for the Extra Tectonic note]
Yes. as was mentioned, you would oscillate back and forth until friction (I am hoping there would be air in this hole) eventually stopped you. Nothing to do with magnetic forces, I'm afraid. Gravity is not caused by 'atomic' or 'subatomic' activities in the least. It is caused by mass, and the center of the mass of an object is where the force of gravity is used to calculate effects. The sum of all the little gravitation interactions between your atoms, and the individual atoms (or molecules) of the earth, ie. on each side of the tunnel, cancel out so that the center of masses is good enough to consider. Of course, if the other surface, the south pole as it were, is further from, or closer to the center of the earth, say a mountain or valley, you might find yourself not reaching the local surface (on the other side) or flying quite far up! We must also neglect the effects of the earths rotation and orbit for a truly straight path to occur. I imagine, anyways!
In our physics classes in high school we studied the phenomenon. The example given by the professor was his: “Theoretically, could be possible to build a tunnel through the Earth crust, from one country to a nearby one (not necessarily to the other side of the planet) perfectly straight and run a train without engines? The theory said the first half of the tunnel would be a downward slope, where the train would catch up speed enabling it to reach the other end of the tunnel (in an upward slope). It came out that it is possible (theoretically) and that the time needed for such a trip will be always 42 minutes, no matter how long the tunnel would be. Mathematically, it would take an object 21 minutes to fall through a vacuum tube to the Earth’s center, and another 21 minutes to reach the other side. Of course, there are some real things that we must leave out of the experiment (as friction and atmosphere), for the impossible task of making a tunnel through Earth’s core (but it could be made from México city to Canada, or London to Berlin, I suppose, where you don’t get too close to the mantle and avoid melting your train and burning the people.
the air at the centre would be pretty thick with a ~6400km column of it. Please Register or Log in to view the hidden image!
Edufer, you're correct. I have also seen that worked out in a Physics text. The length of time travelled in freefall through a vacuum tunnel between any 2 point on the planet's surface is independent of the chord that makes up the distance between them. Trip takes 42 minutes. The air pressure thing is interesting. At any point (not just the centre) inside a uniform spherical shell, the gravity exerted by the shell cancels out to zero. The gravity of the earth would be zero if you could stand at the exact centre (if it wasn't thousands of degrees Kelvin). I think that would necessarily make the air pressure zero.
As gravity decreases in our theoretical trip to the Earth's center, the weight of the air column will decrease exponentially from the surface to the center (it increases exponentially from the top of the atmosphere down to the surface), so the weight of the air column in our theoretical tunnel would increase somehow for the first few kilometers down the tunnel, and then will start to decrease as gravity decreases. At least, that's my wild guess. Any dissenters? Or a better theory?
Theoretically, if the earth is a uniform density sphere, the air pressure would decrease linearly from the surface to the centre. The gravitational field below the surface is proportional to the decreasing radius. Above the surface of the planet, it is proportional to 1/r^2.
About air pressure: Edufer said it correctly: “weight of the air column will decrease exponentially from the surface to the center “ Flunch restated the idea incorrectly: “the air pressure would decrease linearly from the surface to the centre. “ (The air pressure in a sealed tube with one atmosphere at both ends is one atmosphere at the middle, even in a zero gravity field.) Odim’zim said the following: “you would Be stuck in the centre of the earths gravitational feild and crushed.” Which makes so little sense I can’t tell what he is saying. I note he displays a red star and is concerned about being “stuck.” If you were to get “stuck” it would be probably at the Chinese imigration office and I can see how that might “crush” one.
Your smoked corpse would bounce back and forth (oscillate) between N and S before finally stopping in the core, and melting.
Not quite. The incremental weight of each extra kg of air in the column will decrease to zero, but the accumulative weight will (funnily enough) accumulate. The air at the centre will weigh nothing, but it still has to support the entire column, which does weigh something. So, the pressure in the middle will be huge. I did a spreadsheet to calculate this a while ago, and found that the atmosphere would actually become liquid long before you get close to the middle.
In a uniform, zero-gravity field - yes. Otherwise, not necessarily. Example: Consider a large upright, U-shaped tube, full of air, sealed at both ends. Each end at 1 atmosphere pressure. If it is subjected to the gravity of a large body like earth, there would be a measurably larger pressure at the bottom of the U due to the column of air above this point. And in our case we have a fluid column subjected to a decreasing gravitational field as we descend. But though decreasing, there is force at every point except for the exact centre. Pete, I also did a spreadsheet today on this. I tend to agree. At the centre you'd be weightless but the air pressure would be huge.
