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MyHeadHurts
2004-Oct-15, 07:52 PM
i have already posted this thought exercise b4....but i enjoyed the replies so much i thought i'd get some new ppls ideas. and i refined it a bit...here goes.
lets say we could put a astrodome sized room centered at the gravitational center of the earth, built to withstand the pressure and heat and all that. now if you released a bowling bowl in that room....
what would it do?
float to the center?
straight line or an arc?
would it stay in the center motionless?
would it wobble?
what kind of effect would the moon and sun have upon it?
would it float at all?
what other things not mentioned would influence it?
hummmmm
:ph34r:

StarLab
2004-Oct-15, 08:01 PM
Well, it would go to the surface,believe it or not, because the center of gravity is somewhere in the mantle, due to the presence of the moon.

John L
2004-Oct-15, 09:24 PM
I think if you were standing in the Mass Center of the Earth then it would stay exactly there. If we were at one of the walls of your subterranian Astrodome and dropped it, it would accelerate toward the center, move past it, decelerate as it went away, come to a stop, and begin accelerating toward the center again. Friction with any ground like surface or air inside would cause each repeat of this cycle to grow smaller and smaller until it settles in the center.

As for StarLab's response, I think that any gravitational effect of the Sun or Moon felt by an object inside the center of the Earth would be negligible compared to the nearby mass of our entire world. I could be wrong on that, though. If StarLab is right, then it would fall to the outerwall closest to the Moon and roll around the wall at a spot closest to the Moon as the Earth rotates on its axis and the Moon orbits the Earth.

Guest_Nicolii
2004-Oct-20, 12:15 AM
What about the motion of the Earth? Would it's momental force dominate over the gravitational attraction of the Earth and external masses, causing the ball to roll and stop at the wall opposite of the Earth's motion? If not that dominant, it would at least have some effect upon the ball. We need a physist to consider all of the factors of this puzzle and calculate their effects upon the ball to conclude this question!

Guest
2004-Oct-20, 01:26 AM
It would constantly be on the side of the room that is closest to the moon. It would 'orbit' this room every 28 days.

TheThorn
2004-Oct-20, 02:41 AM
Originally posted by Guest@Oct 20 2004, 01:26 AM
It would constantly be on the side of the room that is closest to the moon. It would 'orbit' this room every 28 days.
Close. It would constantly be on the side of the room closest to the moon, which means that it would "orbit" the roon in about 23 hours. (i.e. it would make 29 circuits in 28 days).