If you dug a tunnel from equator to equator, and sealed the sides

what would happen to you if you jumped into the hole?

And how would that differ from jumping into a hole dug from north to south poles?

If you made a tube in space 1 foot wide and 200 miles long and welded only one end shut, then dropped the welded end into the ocean and then cut off the end while it was submerged, would the ocean get sucked into space?

What if you made a circular space station around a black hole at exactly the radius where light goes in a circle around the black hole? Would it be possible to make the space station rotate so the centrepetal force keeps the space station from being sucked into the black hole? If so, what would it look like to a person inside the space station?

These are important questions to me and I am going to try to see if I can do some of these things someday. =P

To solve it classically you need to make certain assumptions. The Earth is a perfect sphere, has uniform density, there is no friction, etc.

The short answer is you fall. Accelerating all the way but the acceleration rate decreases all the way until you reach the center of the Earth where the net gravitational attraction reaches zero. Of course, you have been gaining velocity the entire way so you have a lot of inertia and/or kinetic energy built up (depending on how you want to look at it) so you will continue "up" the other side, steadily losing velocity until you reach zero velocity at the portal on the other side. If you do nothing you will immediately fall back into the hole and repeat the process in reverse. Assuming no loss of energy due to friction you will have become an oscillator with a period of about 90 minutes. Sort of a DULover version of Old Faithful.

Drilling in any fashion other than from pole to pole would create coriolis forces from the Earth's which would pull you to one wall so instead of falling, you would essentially be sliding. Drilling the hole from pole to pole eliminates the coriolis problem.

The passive ocean sucker fails the conservation of energy test at first blush. So before we even think about the mechanics, we have to ask where did all the energy come from to space the ocean? Any way I look at it I see a system with more energy than it had before. I think the atmospheric and hydraulic pressure at the depth of the hole would simply push the water up to a little higher than the surounding sea level. Since it is open to the vacuum of space, it would elevate the water to an amount equal to one atmosphere, i.e. abour 34 feet.

The space station or craft orbiting just outside the event horizon of a black hole. Sure, in theory. I suppose that it would look dark :rofl: unless there is matter getting dumped in as in from a companion star.

Unless the hole is pole-to-pole, you get scraped raw against the sides as you shed the angular momentum you had on the surface.

Always a consideration when there's motion in a rotating frame of reference.

Dear Cecil:

You may recall that Alice wondered about how deep the tube was while she was falling down the rabbit hole into Wonderland. If such a frictionless tube actually did exist, and went from the North Pole to the South Pole, and you or I accidentally stumbled into one of its open ends, exactly what would happen to us? --Larry W., Baltimore

Whenever this job starts to get boring, I know I can count on one of you screwballs out there in Baltimore to come up with something. You guys are a national asset.

What we are dealing with here is essentially a cosmic pendulum. But let me explain a few basic concepts first. For one thing, we are going to disregard the problem of the earth's molten interior. There is no surer way to ruin a good discussion than to contaminate it with the facts.

Next, you must force yourself to accept the following notion: if you were somehow teleported to a cave in the center of the earth, you would find that you were weightless. This is because you would have approximately equal amounts of mass on all sides of you, which would cancel each other out.

Now then. If you jumped into a frictionless (and consequently airless) interpolar tube, you'd fall, obviously, picking up momentum as you went. As you approached the center of the earth the pull of gravity would decline and eventually (at the center) cease, but inertia would keep you going.

Once past center, though, the pull of the earth's mass behind you would begin to slow you down, at exactly the opposite rate that you'd accelerated. You'd come to a complete stop just at the brink of the Antarctic end of the tube, where you'd have an opportunity to wave gaily to the bunny rabbits or whatever they have out there before beginning to fall back in the opposite direciton. This process would continue forever.

Once we start figuring for the effects of atmospheric friction, of course, the situation changes. After a certain point in the course of falling you'd reach a top speed called "terminal velocity," where air resistance would counteract the accelerating effects of gravity. With less momentum, you'd only fall a relatively short distance past the center of the earth before you stopped and started heading in the other direction. Eventually you'd reach equilibrium at the earth's center.

I was going to calculate how long this would take, but twenty minutes of computation has produced no useful result and you didn't ask anyway. But watch where you're going.

--CECIL ADAMS

http://www.straightdope.com/classics/a1_165.html

Cecil is GOD!

First, you fall, but air resistance will limit your speed. Once you pass the center, gravity would stop you pretty quick, but no matter, you'd already be a cinder. It's hot down there. I'd recommend an asbestos suit, if asbestos weren't so hazardous to your long-term health.

If the hole was dug pole-to-pole, same outcome, except you'd start out colder.

Vacuum of space doesn't suck water. It's the air pressure on earth that pushes it. And it can push mercury about 3 feet (how many inches in a normal barometric reading?). Water can get pushed farther, but only about 30 feet? I'm too lazy to look it up. The ocean would be safe from your puny little soda straw.

Black holes are beyond my comprehension. But to get the centripetal force to overcome light-stopping gravity, you might need to push past the speed of light. Better get a big V-8 under that hood.

These are all much better questions than anything dealing with issues in the primary. Thanks.

:hi:

There is only one, you know.

And anyone on it.