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Post by abacus9900 on Feb 17, 2011 15:06:22 GMT 1
If you could travel to the very centre of the earth would you still experience the same gravitational pull you do on the surface and if not why not?
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Post by speakertoanimals on Feb 17, 2011 15:25:36 GMT 1
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Post by abacus9900 on Feb 17, 2011 15:27:59 GMT 1
I mean what is the friggin point?
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Post by speakertoanimals on Feb 17, 2011 15:30:48 GMT 1
I dunno, you keep asking and re-asking the same questions that you could find an answer to in about 30 seconds by googling, or looking at a decent physics FAQ.
Except you don't, you just keep dangling them here as some sort of demented bait -- except I keep biting it off, hook line and sinker (dearie me, getting too fishy here methinks.................)
The shark of the boards cruises back into the cerulean depths. Cue scary jaws music........................
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Post by Progenitor A on Feb 17, 2011 15:48:56 GMT 1
If you could travel to the very centre of the earth would you still experience the same gravitational pull you do on the surface and if not why not? Take no notice of th edisturbed one Abacus, she cannot help herself and any feedback causes instability Inside a spherical shell (no matter how thick the shell) the summation of the gravitational fields at any point is zero. You might think that as you stand on the inside shell, then the gravity of the mass you are standing on will cause you to stay there. But every point on the inside of the shell is also pulling at you with its own gravitational force Thus opposite from where you are standing, you will have a similar gravitational force acting upon you, but because you are further away from that part of the shell its effect is less. But that lessened effect is made up for by all the other points pulling at you with their gravitational force, and the overall effect is that these small accumulation of forces are equal and opposite to the force you experience where you are standing (Of course you will not be standing but floating in a zero gravity field) |
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Post by abacus9900 on Feb 17, 2011 16:01:37 GMT 1
If you could travel to the very centre of the earth would you still experience the same gravitational pull you do on the surface and if not why not? Take no notice of th edisturbed one Abacus, she cannot help herself and any feedback causes instability Inside a spherical shell (no matter how thick the shell) the summation of the gravitational fields at any point is zero. You might think that as you stand on the inside shell, then the gravity of the mass you are standing on will cause you to stay there. But every point on the inside of the shell is also pulling at you with its own gravitational force Thus opposite from where you are standing, you will have a similar gravitational force acting upon you, but because you are further away from that part of the shell its effect is less. But that lessened effect is made up for by all the other points pulling at you with their gravitational force, and the overall effect is that these small accumulation of forces are equal and opposite to the force you experience where you are standing (Of course you will not be standing but floating in a zero gravity field) Ahhhhhhhh, gotcha! So because you are being pulled by gravity in every direction everything cancels out and you will be in a zero gravity field! Yes I hadn't thought of it that way - by the time you reach the centre of the earth there's more mass 'outside' of you so you get pulled outwards rather than inwards. Cool.  |
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Post by speakertoanimals on Feb 17, 2011 17:20:49 GMT 1
Except you don't if the net pull is ZERO.
You NEVER get pulled outwards whilst moving to the centre (not FALLING, because if you actually fell, you'd be weightl;ess so not feel gravity anyway!), because the net effect of the mass outside you is ZERO. Hence all you do feel is the effect of the mass that is still closer to the centre than you are.
In fact, gravity could actually increase as you went down a radial tunnel, depending on the exact way density changed. SO you'd have LESS total mass inside your position in that case, but you'd be closer to it, so possible to get an intial increase over gravity on the surface, then decreasing again until zero when you are at the centre (which is fairly obvious anyway, if at the centre symmetry dictates no net force. Showing there is no net force if there was a spherical cave at the centre is harder -- but knocks all those hollow earth fantasies on the head!).
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Post by abacus9900 on Feb 17, 2011 21:35:10 GMT 1
Except you don't if the net pull is ZERO. You NEVER get pulled outwards whilst moving to the centre (not FALLING, because if you actually fell, you'd be weightl;ess so not feel gravity anyway!), because the net effect of the mass outside you is ZERO. Hence all you do feel is the effect of the mass that is still closer to the centre than you are. In fact, gravity could actually increase as you went down a radial tunnel, depending on the exact way density changed. SO you'd have LESS total mass inside your position in that case, but you'd be closer to it, so possible to get an intial increase over gravity on the surface, then decreasing again until zero when you are at the centre (which is fairly obvious anyway, if at the centre symmetry dictates no net force. Showing there is no net force if there was a spherical cave at the centre is harder -- but knocks all those hollow earth fantasies on the head!). Sorry but I have to believe naymissus cos he's a better teacher and has been right so far. |
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Post by speakertoanimals on Feb 17, 2011 21:48:50 GMT 1
Except this is SCIENCE not religion -- belief not required, go check for yourself!
Or at least attempt to evaluate WHY something is said to be wrong when someone claims it is.
Of you could just follow the first freindly idiot you come across, your pigeon...............but you'll stay in error if you do.
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