Imagine a tunnel ran directly through the centre of the planet, connecting two opposite points in the ground. What would happen if someone were to jump in?
Would you shoot out the other end? Stay floating in the middle? Implode? Explode?
(Please forget the planet collapsing or person melting (unless you’re sure it’s relevant) by adding some special pipe and cooling device!)
The following must be assumed for an easy answer:
If #1 is met then you can ensure that you won’t hit this side and slow down due to friction. If 2# is met you can ensure that you will pop out right at the other end and just hop back on your feet on the edge of the exit, or be shot way up and land.
You’d oscillate between the poles until you got stuck in the center.
or be grabbed by your buddy at the other side. Of course due to air friction you probably wouldn’t make it to the other side.
Air friction? um how about simple cooked in the oven. I may not have attended school for a few decades but, I do seem to recall that the center of this planet is rather hot. The closer you get the more you get cooked. your body won’t come out the other end. heck, I doubt there would even be any ashes.
The vaccuum created by allowing the hot air to escape is the primary reason you won’t go very far. You will be pushed up by the rising hot air and probably slow roasted in its column. All of this will probably occur in the air not within the planet Yum, Long pork, Rub yourself with BBq sauce cuz sun creen just won’t cut it. 
That all is depending upon wether you get close enough to the tunnel. The toxic gases and incredible ground heat will kill you before you even get close.
but Kris I mentioned that a special air-cooling device would be included, making the air suitable for human passage.
I think Xunz had the right answer - we’d oscillate back and forth until a standstill at the centre. How fast and far this “swinging” would be is a further curosity. Also, I’m still sceptical as to whether the gravity at that point would not rip us apart.
LOL and just who would you get to volunteer to put the cooling device there? Not me, no amount of money could budge me on that. Thermal suits just don’t have that kind of protection. The world couldn’t collapse. it might explode, but, not implode. Pressure is being forced out not in. Wonderful thought. 
I wonder if a meteor could ever do that?
Xunzian is probably right because, of gravity if you survived that is. Gravity might tear you up the closer you are to the axis of the world it would be spinning faster, I think.
do you know how divers get the bends when they go too deep? I figure once you have fallen 200 feet below sea level (give or take a bit) your lungs will have contracted enough (the air pressure gets greater the deeper one goes) to stop breathing completely…
-Imp
Assuming the mass of either side was perfectly equal, I believe that we would be stuck in the middle.
If the mass of either side was significantly greater, from a vertical standpoint, one would be drawn to the middle, but would be entrapped (horizontally) on one of the sides.
Please add the words, “I think,” to both of those statements, I forgot to and didn’t feel like using the mosue to get back up there because it’s battery is dying.
that’s an interesting point.
so what if we say it is a vaccuum (and we had space-suits on)?
please Kris, cut me a little hypothetical slack!
If a meteor fluked such a perfect hit, I think it would implode and go back to normal. But our special pipe eliminates any implosion. I don’t see how it would explode.
Yeah, so we could be “floating” in the centre in perfect synchronicity with the orbit and spin of the Earth (so only one spin every 24 hours is pretty slow).
I agree. Perhaps leaving the hold of the centre would require a similar push or pull to that needed for leaving the atmosphere.
(Hard luck with the mouse!)
closer to the axis it is a faster spin, I thought , I must have it backwards, I will cut you slack if you cut my math slack, I have been away from math texts a long time. 
Could a meteor punch a hole ight through the planet with out exploding the planet? I wonder how fast it would need to be going? Is it possible that a meteor could travel fast enough? Would the shape of the meteor have to be a factor?
then xunzian’s point would be most likely correct
-Imp
The batteries have since been replaced.
= The answer. Add spinning in the center for a more complete answer.
hey, my maths is lame with a capital right angle!
play around with the variables (shape and speed) enough and I expect it would be possible to punch a perfect hole right through. but given the size of the planet, one would first have to ensure that a speed lower than that of light’s would be sufficient; otherwise you’re doomed from the start.