A hole through the centre of the Earth

[Ian King]

If it was possible to drill a hole say 100 meters in diameter through the dead centre of the Earth and I was to jump in, what would happen? What would happen if I came through the other side? Ignore the heat, pressure and the fact that I may hit the sides. Always wonderd this since I was a kid.

[Mattk]

ingoring those factors...you'd hover in the middle as there would be no up nor down !

[Relayer]

You would jump, reach maximum velocity and the force of this would carry you beyond the centre some distance before the force of gravity counteracted on you, so I'd have thought you would oscillate about the centre several times before coming to rest. You would then only be able to escape hovering if you had remembered BEFORE jumping to strap on your rocketman backpack to escape Earth's gravity in the same way as surface-dwelling astronauts do now.

[Mattk]

ummm so you'd hover ? think i already said that

[bernardo]

When Relayer said "and the force of this would carry you beyond the centre" he/she meant "and the momentum of this...".
You would go as far as the surface of the Earth on the other side before falling back in again. The only thing to make you settle down in the middle would be the air resistance, which would gradually slow you down.

[FTVS]

bernado why wouldn't gravity affect you?

[Drewhound]

Gravity would take you to the centre where you would reach maximum speed, it would then act in exactly the opposite way and stop you just as you reached the surface, As bernardo says air resistance would slow you down so you wouldn't quite get to the other side This ignores the pacific ocean which would be coming the other way making it a rather wet experience

[thekraut]

Great, finally someone thinking the same things as me! Fact is, that you would oscillate around the earths center before finally ending up in the gravitational center of the earths mass. Just like a week or so of bungee jumping. well, so far its not very different from what all the other guy said, but be careful that the rotation axis of the earth is in the middle of your tunnel. otherwise you would hit the wall before you could say "what the...?" because the coreolis force would grab you pretty badly.

[thekraut]

coeolis, coriolis, choreolis, choriolis.....? or maybe choraeolees?

[buchanan]

But where do you get the "rocket man backpack" that Relayer refers to? They sound like fun

[Drewhound]

Didn't they use some of those jetpacks in the Sydney olympics? But not for the high jump I hope

[bernardo]

FTVS - but gravity would affect you. It's the gravity which makes you fall towards the centre of the earth in the first place. After you've fallen all the way to the middle, it's the gravity which then slows you down again while you're on the way out again, and then makes you fall inwards again. It's a bit like a thingy on a string swinging backwards and forwards - when you pull it sideways and let go, it doesn't just go to the middle and stop; it goes swing-swang both ways a few times before converging to the middle.

[Astraz]

Jetpacks in the Sydney olympics? What event was that in then, the high jump or the pole vault, and did the winner get a world record ?

[Calvesy]

If the tube were evacuated, and went from pole to pole, it would take you about 40 minutes to travel the length of it. At the core your speed would be same as that of satellites in low orbit (8km/s). Density of the Earth is not uniform as the heavy metals have fallen to the core, so higher speeds are reached earlier and scubbed off later compared to mathematical models for simple harmonic motion you might see on other web pages.
If the tube were not aligned with the axis, the coriolis effect would dash you against the side. If the tube contained air you would never fall much faster than 150km/h and would end up weightless and stuck at the core with a 6370km sheer climb ahead of you.