Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Rash on September 23, 2011, 08:29:08 PM
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Say I could drill a hole through the North to South axis of the Earth. I didn't have to worry about hot LAVA or different air pressure between North or South. It's a straight shot from North to South and I drop a can of beer through the North side of this hole. Will my friend Sebastian be able to catch this can of beer on the South end?
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Say I could drill a hole through the North to South axis of the Earth. I didn't have to worry about hot LAVA or different air pressure between North or South. It's a straight shot from North to South and I drop a can of beer through the North side of this hole. Will my friend Sebastian be able to catch this can of beer on the South end?
i think so, but it'd be coming through pretty damn fast. so he might want a glove...
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It should start slowing down, once it goes past the center? Will it even make it to him?
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It should start slowing down, once it goes past the center? Will it even make it to him?
well theres still gravity pulling it to him right?
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Once it goes past half way, the center of mass will be behind the bottle. I don't know the answer, just pondering.
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Once it goes past half way, the center of mass will be behind the bottle. I don't know the answer, just pondering.
you see why kids are so stupid these days? in science class we dont learn this, noooo...we learn about cirrus clouds. :rolleyes:
honestly, teach something that will be useful in life school districts!!! :furious
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Would it matter if I dropped it from the North or South pole?
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Would it matter if I dropped it from the North or South pole?
i dont really think it would considering gravity works both ways.
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He would probably never get it. Ignoring temperatures etc. the can would accelerate towards the center of the Earth, gaining speed until it hits terminal velocity. Once it passes the center it would start being pulled back towards the center. Think of it as a pendulum, starting at one height but never quite making it back to that same height as is swings back and forth until it eventually comes to rest at the center of the Earth.
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He would probably never get it. Ignoring temperatures etc. the can would accelerate towards the center of the Earth, gaining speed until it hits terminal velocity. Once it passes the center it would start being pulled back towards the center. Think of it as a pendulum, starting at one height but never quite making it back to that same height as is swings back and forth until it eventually comes to rest at the center of the Earth.
^This is correct. Terminal velocity and friction would prevent the can from maintaing enough energy to overcome gravity on the second half of the trip.
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theoretically, it's just a vacuum tube delivery system for beer. Like sears use to have. Same all the way through, North to South.
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^This is correct. Terminal velocity and friction would prevent the can from maintaing enough energy to overcome gravity on the second half of the trip.
This is a answer, after 10 or so seconds, it's not going to fall any faster.
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Once it hits the center of the planet, the forward velocity would reach 0 and it would just sit at the core of the planet until crushed by the gravity
DOH! Im a slow typer
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Coriolis forces (yea, spelling, I know) from the earth's slight wobble as it rotates would cause the can to rub on the side of the hole so there would be some energy losses both dropping to the center and coasting on the way back up on the far side. Even if those forces are very small, the can would climb to just below the distance from the center of the earth's mass as it was dropped. Assuming a perfectly spherical earth with uniform density (which is not actually true), if the can was dropped from the exact entrance to the hole, it would not quite make it back up to the surface on the far side. It would cycle back and forth until those very small energy losses cancelled out all of the can's potential energy (dist from earth multiplied by mass) and the can would then be at rest in the center of mass. Of course, all that energy would be dissipated as heat, absorbed partially by the can and partially by the side of the hole (the earth). So it would increase the overall heat of the earth. If you look at the total amount of energy in a can at the surface of the earth relative to it's position at the center of the earth, that's a heck of a lot of heat so unless there was a way to shed all that heat, the can would likely be vaporized long before it quit moving.
Of course, that assumes that all of the air in the hole is evacuated so the can is falling through vacuum. Although this is impossible, it is no more impossible than the original premise of drilling a hole straight through anyhow.
A can-sized object falling to earth from orbit would vaporize from air friction fairly high up in the atmosphere, and that's just the energy being dissipated from an orbit a couple hundred miles up.
Now if the hole was filled with air pressurized to the "sea level" (again impossible), the can would reach terminal velocity somewhere around 200 miles per hour and so it would be effectively braking the entire way down. So it would climb maybe a few hundred feet on the far side of the earth's core and stabilize at the center a lot faster.
If the air increases pressure on the way down to the center of the earth, the can will crumple and turn into a little hot wad of metal, and again probably vaporize from the heat and pressure. Then again, at the pressures present at the center of the earth, I think oxygen and nitrogen turns into a liquid and acts like a metal, so that is sort of a silly condition.
So... Lots of different answers depending on your assumptions.
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Ignoring every factor, wouldn't it climb the same distance it fell? Like the ramp/marble experiment... two ramps same height one going down other going up... drop the marble down one and it'll stop at the same height on the other ramp it was released, if that makes any sense.
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Ignoring every factor, wouldn't it climb the same distance it fell? Like the ramp/marble experiment... two ramps same height one going down other going up... drop the marble down one and it'll stop at the same height on the other ramp it was released, if that makes any sense.
IF you ignore every physical force acting on the can, then yes.
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Terminal velocity was what I was overlooking.
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He would probably never get it. Ignoring temperatures etc. the can would accelerate towards the center of the Earth, gaining speed until it hits terminal velocity. Once it passes the center it would start being pulled back towards the center. Think of it as a pendulum, starting at one height but never quite making it back to that same height as is swings back and forth until it eventually comes to rest at the center of the Earth.
If the air were evacuated, there would be no "terminal velocity" as long as gravity is pulling it towards the center of the earth, unless there is another force acting on it such as friction with the walls of the hole. It would continuously accellerate (or decelerate, which is the same thing) any time it was not exactly at the gravitational center of mass of the earth. On the way "down" it would accelerate continuously until it passes the center point, at which it would begin to decelerate (accelerate in the opposite direction) until it came to a halt (in a perfect system it would rise to the exact height as it was dropped from), at which point it would start back down the other way.
What we're really quibbling about are what factors prevent it from being a perfect system. If it were a perfect hole evacuated to a perfect vacuum and the can fell with no friction from the walls or other factors causing it to lose energy, it would cycle back and forth forever. But no system is perfect, and even a miniscule amount of wobble in the earth's rotation and the precession of the earth as it zings around the sun would cause the can to press up against the wall of the hole just a tiny bit. That factor alone would be enough to gradually transfer the can's energy into heat, even if the rest of the system were "perfect" with no friction or other sources of energy loss.
Oh yea, don't forget those other sources of loss. If the can is metal and passes through rocks with different magnetic or electrical properties, magnetic flux forces will be generated which will again transfer energy to heat.
So, we're quibbling about sources of energy loss, because although in a perfect system it would oscillate forever, the system simply cannot be perfect if for no other reason than the earth is tipped a bit on its axis as it rotates around the sun, and that would cause the wall to have to exert some force on the side of the can to keep it going up and down the hole. And that's just one source of energy transfer/loss.
Then again, if you build the can right, some of the energy lost to heat could be used for propulsion. Having one end of the can a better radiant surface, for example, would create a miniscule amount of thrust as the heat created by the friction was radiated from the can. For that matter, you could use energy transfer from the hole to the can to actually ADD energy to the system, so the can would actually oscillate farther and farther each time through. If the walls of the hole transferred heat energy to the can, and the can was designed so that the radiated energy was always directed in the direction that the can was travelling, then the can would accelerate faster than the acceleration caused by gravity. That additional acceleration could be calibrated to exactly counteract parasitic losses due to can-hole friction, earth wobble, losses due to magnetic flux, etc.
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Ignoring every factor, wouldn't it climb the same distance it fell? Like the ramp/marble experiment... two ramps same height one going down other going up... drop the marble down one and it'll stop at the same height on the other ramp it was released, if that makes any sense.
No. Terminal velocity comes into play because of the distance involved. Your marble experiment doesn't work when the distances become greater then the distance required for the marble to reach terminal velocity.
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In a vacuum, If you dropped it 2 feet above the hole, it should arrive 2 feet above the hole?
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Is there a pressure were terminal velocity = 2 mph's?
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Terminal velocity was what I was overlooking.
There is no terminal velocity in a vacuum, unless there is another force acting on the object. The whole concept of terminal velocity simply describes the point where the force of gravity is exactly balanced by some other retarding force (usually drag from movement through air). Remove the air, and you have no drag, hence no terminal velocity.
There are other possible sources of external force however, so we need to either talk about which forces will be included, or assume that every other force other than gravity is zero.
Even in space in "hard" vacuum, especially in the vicinity of a solar system, there will always be other forces. The solar wind has enough force to create a "terminal velocity", or even be used for propulsion. The voyager spacecraft had weird acceleration profiles that caused people to suspect all sorts of explanations, until they realized that the simple heat from the power supply (nuclear) was enough to give the spacecraft a slight acceleration. We're talking about less heat than a warm frying pan, but over many years that adds up to a noticeable delta-V.
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No. Terminal velocity comes into play because of the distance involved. Your marble experiment doesn't work when the distances become greater then the distance required for the marble to reach terminal velocity.
You have to assume that the hole has no air in it, because at the pressures in the center of the earth, air would be compressed back into a liquid and the can would splash down and stop well before it got to the center. No air = no "terminal velocity", unless you postulate some other force that increases as velocity increases. Magnetic flux as a metal can passes through layers of dirt with slightly different magnetic fields, could be one such source of an external force that could retard movement. But now we're quibbling about what forces we keep while throwing all the rest out.
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In a vacuum, If you dropped it 2 feet above the hole, it should arrive 2 feet above the hole?
"Yes", minus energy sapped from other sources of loss/transfer.
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Sorry, I said this wrong....what is the pressure at terminal velocity = 2 mph's
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You have to assume that the hole has no air in it, because at the pressures in the center of the earth, air would be compressed back into a liquid and the can would splash down and stop well before it got to the center. No air = no "terminal velocity", unless you postulate some other force that increases as velocity increases. Magnetic flux as a metal can passes through layers of dirt with slightly different magnetic fields, could be one such source of an external force that could retard movement. But now we're quibbling about what forces we keep while throwing all the rest out.
Some piraticals can just pass right through Earth with no effort.
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Is there a pressure were terminal velocity = 2 mph's?
Drop a rock in a swimming pool, to answer that question.
Air is simply gaseous oxygen, nitrogen, Carbon Dioxide, and other trace gases. Water is simply liquid Oxygen and Hydrogen. "air" happens to be gaseous at sea level, while water happens to be liquid at sea level. Reduce the pressure and water turns into a gas. Increase the pressure and air turns into a liquid. Increase the pressure too much and, if I recall my chemistry and physics lessons correctly, that liquid will take on most of the characteristics we associate with metals.
At the center of the earth, the pressure is high enough that air would be a liquid, leading to the same sort of terminal velocity you'd see from dropping a rock into a pool of water.
You could increase the air pressure to just below the pressure required to liquify it, and the terminal velocity would also drop because the air would be a lot more dense (more molecules to run into). At that point you need math to figure it out because the exact composition of the "air" and the density/mass/shape of the dropped object would become really important. For example, a "can" flattened out until it is as thin as tinfoil, dropped through regular sea-level air, has a pretty darn low terminal velocity. So shape and density of the object and the components in the "air" become really important if you want to target a specific terminal velocity for any given object or medium through which it is passing.
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Some piraticals can just pass right through Earth with no effort.
They're just really small and moving really fast. They're still getting acted on by the earth though... Even the earth's magnetic field should divert the particles by just a tiny bit.
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That bothers me.
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i would dive in after it and drink it before it got to him
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i would dive in after it and drink it before it got to him
Seems like it would have made more sense to sit down, drink the beer and ponder the possibilities
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If it always passed through the center at terminal velocity, wouldn't it keep going the same distance? All outside factors rendered null, it would be like swinging a big pendulum.
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If it always passed through the center at terminal velocity, wouldn't it keep going the same distance? All outside factors rendered null, it would be like swinging a big pendulum.
If you ignored EVERY potential force except gravity then yes. Otherwise there are myriad forces acting on the can that will slow it down.
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you guys smoke a lot after the sun goes down I think. :neener:
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you guys smoke a lot after the sun goes down I think. :neener:
Friday is smoking day, but it's apple or hickory.
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I was going to ask, who LSU was going to loose to this week?
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Say I could drill a hole through the North to South axis of the Earth. I didn't have to worry about hot LAVA or different air pressure between North or South. It's a straight shot from North to South and I drop a can of beer through the North side of this hole. Will my friend Sebastian be able to catch this can of beer on the South end?
it would do two things, ethier
emploded when close to center due to the magnetic field
or would simply float in the center
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Oh yeah, like there is even a chance a can of beer would get past the little people underground.
:x
NwBie
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We don't need any negative imploding Old's waves, keep them to yourself babe.
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Oh yeah, like there is even a chance a can of beer would get past the little people underground.
:x
NwBie
I like how you think!
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If it always passed through the center at terminal velocity, wouldn't it keep going the same distance? All outside factors rendered null, it would be like swinging a big pendulum.
Look at some extremes.. You drop a feather from a mile up.. it's terminal velocity might be 5 miles an hour.
If you turned around and threw that feather back up at 5 mile per hour, do you think it would have enough E to go up a mile?
Same thing for a piece of paper..
I use those two examples to give a better visualization of what air friction can do to an object.
Keep in mind, there's no terminal velocity in a vacuum. ( hammer vs. feather drop )
http://www.youtube.com/watch?v=5C5_dOEyAfk
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I'm thinking if a beer can were exposed to a near 0 psi vacuum. The can would probably burst open. Especially because water boils at just above 32 deg F (0 deg C) at 0 absolute psi.
Aside from exploding if the can didn't experience any type of friction resistance. Then yes it would reach the opposite side of the earth.
Personally, I would probably drink the beer first and then pee into the hole. Then I would call the guy on the opposite side of the earth and tell them to get ready to catch it :t
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here's to physics! :cheers:
oops I think I just drank your experiment :bolt:
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42 minutes.
http://www.youtube.com/watch?v=EapvQ3ALYJY
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I wonder what would happen if either one of you was in a dry country. or perhaps dropped the can on a sunday morning. you would both go to hell.
semp
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This thread is full of win!! I love physics :banana: