milan666 Posted December 29, 2005 Posted December 29, 2005 This is a very serious question for all of you nerds. Who ever can answer it is the smartest nerd of all nerd. If i dig a hole through the Earth (from one end to another), then if i jump through it, will i fall out the other side or what? Because when i jump in it i will be falling DOWN but how could i come out the other side falling DOWN. Thats impossible. Someone please answer this question.
YT2095 Posted December 30, 2005 Posted December 30, 2005 no you`de Not come out the other side, you`de more or less stay in the middle because you`de be pulled by gravity equaly in all directions by a force of 1G. effectively you`de have as much Earth mass pulling you down as trying to pull you back up again in the middle
timo Posted December 31, 2005 Posted December 31, 2005 This is a very serious question for all of you nerds. Who ever can answer it is the smartest nerd of all nerd. ... or the only one bored enough to reply ... I hate Sylvester. If i dig a hole through the Earth (from one end to another), then if i jump through it, will i fall out the other side or what? Assuming no air resistance and earth to be perfectly spherical, then "yes". Because when i jump in it i will be falling DOWN but how could i come out the other side falling DOWN. You´d be falling down (and accelerate) until you arived at the center of earth. There, there´s no gravitational force pulling you anywhere (-> the gravitational force of a spherically symmetric body with uniform mass-density goes proportional to the radius and points inward) but you´d still have the velocity (-> kinetic energy) you gained when accelerating. Therefore, you´d pass through the center towards the other end of earth. On the way there you´d constantly decelerate ("fall up") because gravitation tried to pull you down to the center. When there´s no air resistance and if earth is perfectly spherical, conservation of energy guarantees that your trip ends exactly on the other side of earth - but you should hold on to some handle or so or you´d be pulled back again. If there is air resistance, you would lose some of your energy to the friction. Then, after you had passed the center of earth you wouldn´t have enough energy left to reach the other end of earth. You´d stop somewhere on the way being sucked back to the center. This process would repeat for some time untill you´d end up floating in the center of earth ( -> dampened oscillation). Having no (effective-) force (at the center of earth in this case) means that veloctiy remains unchanged, not that there is no more movement (-> the time-derivative of velocity is proportional for the force: dv/dt = a = F/m). If you already arive with some velocity (like when you fell down to the center of earth) you´ll simply keep the velocity (for the timspan of being in the area without force).
the tree Posted December 31, 2005 Posted December 31, 2005 Actually I don't think you'd instantly stop, in fact I think that you'd carry on to half way between the centre and the surface after having fallen into the centre before you urm, fall again.
[Tycho?] Posted December 31, 2005 Posted December 31, 2005 You would fall, reach the center, continue to "fall" upwards until you reach the distance from the center that you started at, just on the other side. You would then fall backdown, go back up, and keep on repeating this motion. Assuming zero kinetic energy is lost throughout this process.
NeonBlack Posted January 3, 2006 Posted January 3, 2006 The smartest nerd of all nerds? Ha! Actually, anyone who's taken freshman physics would know this.
stsanthony Posted January 3, 2006 Posted January 3, 2006 i think so, but adding something onto the previous so, before you reached the centre of the earth, you would melt and die...this question cannot show you are the smartest people in the world but can show people's applications on physics actually....
YT2095 Posted January 3, 2006 Posted January 3, 2006 therein lies the problem between my answer and some of the others, being of a Practical nature, Air resistance cannot be excluded, there would come a point when acceleration would stop and terminal velocity is reached, and depending on the dia of the hole terminal velocity would be slower than freefall without "walls" roughly 200mph wouldn`t be anywhere near enough to get you back out the other side. Very damped oscillation would be the case here. I`ve allowed myself the indulgance of ignoring the heat in the middle too.
Klaynos Posted January 3, 2006 Posted January 3, 2006 therein lies the problem between my answer and some of the others' date=' being of a Practical nature, Air resistance cannot be excluded, there would come a point when acceleration would stop and terminal velocity is reached, and depending on the dia of the hole terminal velocity would be slower than freefall without "walls" roughly 200mph wouldn`t be anywhere near enough to get you back out the other side.Very damped oscillation would be the case here. I`ve allowed myself the indulgance of ignoring the heat in the middle too.[/quote'] In that case why are you ignoring the massive pressure and heat *cough innocent look*
YT2095 Posted January 3, 2006 Posted January 3, 2006 Coz it`s the holliday period, and because I`m worth it
mrblond5311 Posted January 4, 2006 Posted January 4, 2006 The smartest nerd of all nerds? Ha!Actually' date=' anyone who's taken freshman physics would know this.[/quote'] Geesh even I knew that one & I'm just a wannabe nerd! I have a bit of a better question. How much force would it take to come out the other side and could a human body hold up to that force? With or with out a "vehicle" protecting them.
mrblond5311 Posted January 4, 2006 Posted January 4, 2006 You would burn when you reach the center! Well, we know that but I'm sure they meant it in more of a hypothetical way.
chemfreak Posted January 5, 2006 Posted January 5, 2006 Assuming no air resistance and earth to be perfectly spherical, then "yes". Ahhhh but the earth is an oblate spheroid
sunspot Posted January 7, 2006 Posted January 7, 2006 The classical model of your question is similar to a spring. One would begin with highest gravitational potential (stretched spring). The highest velocity would be in the center (no stretch). and then gradually lose kinetic energy as the gravitational potential energy increases (stretches again) to max; one would pop out the other side the same height. The spring analogy would continue indefinately unless friction used up some of the potential/kinetic energy. What is interesting is that the center of gravity of the earth has no gravitational force, since the vectors will all cancel; assuming spherical symmetry. As such, in the center of the earth there is no net gravitational force even though the pressures are at a maximum, with the maxumum gravity potential or pressure coming from the surface.
GORDON HERMA Posted January 12, 2006 Posted January 12, 2006 As you started falling you would start to be pulled by gravity from all sides and behind you the further you fall.The gravity pulling you down initially would still have the greatest amount of force. The deeper you get into the earth the more angled the lines of force being exerted on you become untill they are pulling from every direction inside the core with equal force. Since the angles of these lines of force that caused velocity will equilize themsleves around you in a shpere at the core........ I say you would fall slightly past the core, then get pulled back to it and be stuck in a stand still. Suspended just like a metal pen in a magnetic pen holder.(no strings attached) Now since certain areas of the surface of the earth have different amounts of gravity force associated with them. This would not be a very staight line that you would travel in, it would seem to be a bit of a twisty line as you passed though the different representations of gravity. Not to mention the equalization between the lines of force is probably not the actual core itself, but more off center. How did i do? Gordon..
zking786 Posted January 17, 2006 Posted January 17, 2006 There's no way you would reach the other end of earth when falling through one side. Due to large aerodynamical drag forces (especially in a tunnel!), you can't expect to get too far. I'm not sure how we would take terminal velocity into account, considering our rate of gravitational acceleration is decreasing. Thus, it may be around 9.81m/s/s at the surface of earth, but eventually reaches 0m/s/s at the core. You'd need to use differential calculus to compute a modified gravitational acceleration in motion equation. Then you could deduce whether you would or wouldn't reach terminal velocity. As others have accurately stated, eventually, you would oscillate within the core and ultimately reach the center.
doG Posted January 17, 2006 Posted January 17, 2006 You'd go up like a piece of flash paper before you reached the center since the core temperature is estimated at around 5000 to 7000 degrees Celsius depending on your source.
Pleiades Posted January 20, 2006 Posted January 20, 2006 What about the Earth’s rotation? Wouldn’t freefall towards the center follow a spiral path? I never did ‘get’ circular motion.
Tom Mattson Posted January 20, 2006 Posted January 20, 2006 Come on people, if future humans are smart enough to dig a hole clean through the Earth then they'll be smart enough to evacuate the center, cool the core, stop the rotation, and turn our planet into a perfect homogeneous sphere. Stop nitpicking!
insane_alien Posted January 20, 2006 Posted January 20, 2006 What about the Earth’s rotation? Wouldn’t freefall towards the center follow a spiral path? I never did ‘get’ circular motion. kind of but the effect would be the same; scraping down one side of the shaft.
gcol Posted January 20, 2006 Posted January 20, 2006 The ultimate yo-yo trip. It would sure beat bungee jumping.
Janus Posted January 21, 2006 Posted January 21, 2006 What about the Earth’s rotation? Wouldn’t freefall towards the center follow a spiral path? I never did ‘get’ circular motion. It wouldn't be a spiral, but it would be curved, and your hole would have to be dug such that it misses the center. (Assuming that it isn't dug from pole to pole)
Dbltrimmer Posted June 8, 2008 Posted June 8, 2008 It would seem that anyone who could dig such a hole would also be able to evacuate all the air from it and fall through without any air resistance. Naturally, through the use of an inner and outer tube, which was used to cool the tunnel with water, enough free steam energy could be had in order to power the earth with no greenhouse gasses. The time in seconds it would take to fall through and then come back out the top again would be: (2 [Pi] Sqrt[re])/Sqrt[ge] where re is the radius of the earth and ge is the acceleration of gravity at the surface of the earth, about 5060 seconds round trip. Of course, you would fall all the way through and just come out the other side before falling back in again.
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