dig

xXLoss_of_ControlXx · Post by **xXLoss_of_ControlXx** » 14 May 2006 18:47

Say this was the Earth...

and i dug from red point to black point

would i feel the gravity taking its toll

?

I'm guessing i wouldnt because gravity keeps you straight when walkin from point A to B unless theres a hill...

Another question:

if there was i hole from the north pole to the south pole(i know its not possible cause of the core and all) and i fell in. would i fall on my head? meaning...

would this happen?

or would i end up flipping

brinard · Post by **brinard** » 14 May 2006 20:20

i imagine you would flip several times, as you probably couldnt dig straight. and gravity is starting from the earths center. you would dig up from the center

the logical way to dig is an elongated s shape, or even a spiral.

b

Bander87 · Post by **Bander87** » 14 May 2006 20:34

Brian, I think he meant the question as hypothetic one - with the whole dug already and stuff

I think it depends on your body's center of gravity, which would cause you to flip after you pass the center. Maybe you would get stuck in the middle. We are learning about this stuff in physics, every interesting!

brinard · Post by **brinard** » 14 May 2006 21:10

ah ha.

okay... wel... i think...you would fall to the center...thats for sure. i dont know if you could continue falling... its weird, since thats the center of gravity...

oh well. im not gonna do that, so it dosent concern me too much...

mc · Post by mc » 15 May 2006 07:14

i used to think about this when I was a kid. for the "hole straight through from north to south" question, I think you would fall straight through and ALMOST make it out the other side, but before you got there, you'd start getting pulled back towards the middle, and each time you fell back, you'd be further and further from either of the north or south pole holes, and eventually end up in the middle of the earth, where hell is.

Iron Clad Ben · Post by **Iron Clad Ben** » 15 May 2006 10:36

Are there certain laws of physics we are taking into account and others that we are ignoring? Are you using some sort of drill vehicle to tunnel through the earth's bedrock? Could this device shield you (at least temporarily) from the extreme temperature of the earth's core? Unless you have some serious thermal insulation, you will most likely be incinerated before you reach the earth's core. Also, the force of gravity is going to get stronger as you reach the earth's core. You would need some of propulsion mechanicism to shoot you the other way once you got to the center. Otherwise you would be stuck at the center as you quickly (or slowly if you have insulation) burn to death.

To answer your question in simple terms no you would not flip, because there is no way that gravity can have torionsal effects on you.

Also, how wide is the hole you are digging? Just big enough to fit one human through it? Say 1m x 1m?

Chris Holden · Post by **Chris Holden** » 15 May 2006 11:39

Putting the lethal temperatures to the side, the pressure of gravity would crush you, probably well before you reach the center.

Basically, you’d begin to fall, reach terminal velocity, and the pressures on your body would increase. You would be constricted, breaking all your bones, collapsing your lungs until you were a small mass of flesh and bone. From there, the pressure would continue to increase creating an intense friction heat which would essentially vaporize your body.

Lethal pressure/gravity aside, you’d hit the Earth’s center, even if hallow as stated in the experiment, just as hard as you’d hit concrete. It’s the center of all force (gravity) being pulled in one direction, and the same as the ground pushing against our feet when we walk on it.

cd · Post by cd » 15 May 2006 11:49

Really interesting stuff... it's these kinds of things that made me major in physics in college.

The actual physics would get very complicated if you took into account everything that Ben said. However, if you kept the simple, ideal situation you described, then your motion would be that of a damped oscillator (imagine a spring bouncing back and forth--like Hooke's Law) and you would eventually end up in the middle.

For the first example, red point to black point, the first thing you need to know is that the gravitational field inside a spherical shell is 0 everywhere. That means that if you dig a certain distance into the earth, it will feel exactly like you are standing on a smaller planet; you dont feel any gravity from the outer "shell" you dug through. So, as you start your journey from red to black it would feel like you are going downhill, until you got halfway where it would feel like you are going uphill. Also you would feel lightest at the halfway point and heaviest at either end.

At the very center of the earth, it'll feel like you're floating in space--the force of gravity from the planet around you cancels itself out because it's pulling equally in every direction, so no net gravitation acts on you.

Awesome pictures by the way, especially the last one.

Hakker · Post by **Hakker** » 15 May 2006 11:54

I've actually thought about this alot before. (the strsight down one)

I think once you passed the centre of eath's gravity, you would slow down and go back the way you came, the slow and go down again, and repeat.

xXLoss_of_ControlXx · Post by **xXLoss_of_ControlXx** » 15 May 2006 17:30

Hakker wrote:I've actually thought about this alot before. (the strsight down one)

I think once you passed the centre of eath's gravity, you would slow down and go back the way you came, the slow and go down again, and repeat.

you mean fall>slow>go back>rpt. (hehe)

I'm listening to Chris Dean, he sounds like he knows what hes talkin bout.

chris dean wrote: Awesome pictures by the way, especially the last one.

no prob...(^thats not the reason why)

Bander87 · Post by **Bander87** » 15 May 2006 18:47

Would it be possible to come out the other side if you changed the size of the human and the earth? I mean, you do have some force from f=ma. Could one possibly tweak some numbers so they human builds force to escape the radias of the planet and land on the crust?

xXLoss_of_ControlXx · Post by **xXLoss_of_ControlXx** » 15 May 2006 19:37

Bander87 wrote:Would it be possible to come out the other side if you changed the size of the human and the earth? I mean, you do have some force from f=ma. Could one possibly tweak some numbers so they human builds force to escape the radias of the planet and land on the crust?

i doubt it... well, what i originally wanted to know was "if you were able to come out the other side which way would you land on?"

Larson · Post by **Larson** » 16 May 2006 15:37

At the very center of the earth, it'll feel like you're floating in space--the force of gravity from the planet around you cancels itself out because it's pulling equally in every direction, so no net gravitation acts on you.

I agree with this, it makes the most sense. Although it seems if their was any sort of hole in the center of the earth, it would collapse in because of the way gravity works.

krumpage · Post by **krumpage** » 19 May 2006 17:21

ok now if you dug a hole form north pole to south pole you wouldnt fall on your head. the fact is you would end up being crushed. but lets assume that pressure of the earth does not cave in your little pit and that theres no mass at the ends so theres no pressure forcing you in the center of the earth. i guess yes you would land on your head depending if you went feet in first or head in first. the first question it would be near impossible to dig a hole straight because though you may think all you have to do is dig straight forward. the fact is if you just dug straight you would be digging a curve. but lets assume you know how to make a straight line i guess it would take its "toll" on you. it would be the same as taking a boat there. or walking there and crossing the ocean with a very long bridge. the bridge can help me explain my hole idea where you would dig a curve. when you walk on a straight bridge your still walking on a curve. the bridge curves around the earth making it look straight. but really if you had a straight bridge it would gain elevation with every mile or foot of what ever measurement you want until you reached the atmosphere where im pretty sure it wouldnt be considered elevation anymore

Vpicone · Post by **Vpicone** » 20 May 2006 10:25

plus u have to take into account eart'hs rotation. So, it would really depend on how fast you are going down. If u reached halphway then kept on folling you would probably begin changing directions with earth's rotation.

Jeremy · Post by **Jeremy** » 21 May 2006 19:51

krumpage wrote: the fact is you would end up being crushed.

A few people have put forward this opinion and I think it's incorrect. Yes you would be crushed if there wasn't a tunnel - but presuming the tunnel is structually secure and doesn't collapse as you get closer to the centre of the earth the relative gravity would diminish not increase. Basically if you are in the middle than you have an equal amount of gravity pulling you outwards in all directions and none pulling you in. Gravity is a force of attaction between bodies and if you are in the centre of a body - the mass is around you - so you are pulled outwards in each direction. However the pull outwards is cancelled out by the pull outwards in the opposite direction. In any event the force of gravity given off by the earth is relatively small (but obviously constant). I can easily exert a greater force (for a very short period of time).

Interestingly as I understand it - if your tunnel goes directly through the Earth, (say from Australia to Germany - a rough guess of directly opposite each other) or if it goes through a lesser amount of the Earth (on an angle) - say Australia to the West Coast of the US - the time it would take for a theoretical object to fall through the tunnel is the same (assuming the fall through the angled tunnel is frictionless - ie. isn't slowed down by hitting the sides).

james_dean · Post by **james_dean** » 22 May 2006 17:42

interesting. how does that work, jeremy?

cd · Post by cd » 22 May 2006 22:31

Jeremy wrote:Interestingly as I understand it - if your tunnel goes directly through the Earth, (say from Australia to Germany - a rough guess of directly opposite each other) or if it goes through a lesser amount of the Earth (on an angle) - say Australia to the West Coast of the US - the time it would take for a theoretical object to fall through the tunnel is the same (assuming the fall through the angled tunnel is frictionless - ie. isn't slowed down by hitting the sides).

I don't completely get what you're saying, but I am intrigued.

(just for clarity, we are assuming the earth is a perfect sphere of uniform density and that no outside forces are acting upon it)

The reason why I'm confused is because of the use of the word 'falling'. In the case of the angled tunnel, it would be more like gliding or rolling along the ground... but since we are assuming that there is no friction I guess it's all the same.

One cool thing is that if we ignore those outside forces (such as friction and air drag), then the falling object/person would continue to oscillate back and forth along its path forever, since its total kinetic plus potential energy must always be constant.

So if I understand you correctly, you're saying that this period of oscillation is the same duration of time, whether you go through the center of the earth or some other path? Since you are starting at the same point (the surface of the planet), then the potential energy is the same, regardless of which path you take. So yeah, I agree with you on the falling times... I think there's some law with pendulums which explains this.

sniper4life · Post by **sniper4life** » 24 May 2006 18:33

Well, like Jeremy said gravity is the attraction between objects. Sooo, if you were to cut a hole through the middle of the Earth there would be no object there to pull you to the middle. I have no clue what would happen, but you shouldnt be pulled to the middle of the Earth since nothing is there anymore to pull you. I hope that makes sense.

Jeremy · Post by **Jeremy** » 24 May 2006 21:46

I disagree. Although there wouldn't be anything pulling you directly towards the middle - the mass of the Earth would still be pulling you towards it - and the resultant vector would be towards the centre.