Hole in the world

[Supernick]

If I managed to dig a really big tunnel through the centre of the earth, (dodging melting myself to death), and all the way out of the other side, and then constructed some sort of tube to go all the way through it; if I dropped stuff into my new superhole, would it just end up suspended in the middle?

[Bonzo 2000]

More or less.  The gravitational pull is towards the centre of the earth, so it certainly wouldnt fall straight through.

[booksworth]

OK, here's a first take. Assume there is no air in the tube. What you drop in will accelerate towards the centre of the earth, with the gravitational force acting on it reducing all the while. At the centre there is no net grav. force: your object will carry on going, with the (increasing) grav. force decelerating it. Assuming no air resistance, the object will come to a halt at the surface in the Antipodes, then immediately accelerate back down the hole, and so on. -.-.-.- So the immediate effect is that all intercontinental airlines go broke in short order!. -.-.-.- If the tube did contain air, things you dropped would get very hot, and the oscillations would die down, depositing the objects at or around the centre of the earth.

[thekraut]

I think we alrady had that one before. booksworth, what you say is true, if the hole is dug through the rotation axis of the earth. If not, the coreolis force will bang you to one side of the tunnel and you would end up being hurt pretty badly.

[trilobite]

thekraut is right, but the tunnel would have be big enough to also include the gravitational centre.

[bernardo]

It would go swing-swanging backwards and forwards (like a pendulum) and eventually settle in the middle - but its motion backwards and forwards would only be reduced gradually by air-resistance.

[Phantaxus]

Bernardo is correct you would eventually settle in the centre of the Earth. The only point on the planet with no gravity.

[rod]

If the one end of the tunnel was in line with the moon or sun what effect would that have on an object or water poured down the tunnel?

[Uriah Heep]

When you dug this really big tunnel I assume you piled up the spoil around the enterance.  This would change the shape of the world shifting the centre of gravity towards the entrance hence all objects would eventually come to rest just short of the original centre,