The Earth's core

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psyched

Main Question or Discussion Point

Velocity of the Earth's core

What is the core's approximate velocity?
 
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  • #2
russ_watters
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You mean rotational rate? ever so slightly faster (I think its faster) than the rest of the earth.
 
  • #3
4,464
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Yes, that seems to be the case indeed, the solid inner core spins faster.

http://www.nsf.gov/od/lpa/news/publicat/frontier/3-97/3mysts.htm

Deep within our planet, the Earth's inner core is also spinning -- only it's moving faster than the surface. Every 400 years or so, it will overtake those of us riding on the outside.

This startling discovery was made when two NSF-funded seismologists working at the Lamont-Doherty Earth Observatory at Columbia University took on the challenge of investigating an unproven theory. The theory states that the inner core rotates separately from the rest of the planet, as predicted by an unproven model of the Earth's magnetic field.

Researchers Xiaodong Song and Paul Richards used seismic wave readings from 38 earthquakes between 1967 and 1995. They tracked waves that moved from the south Atlantic, through the inner core, to College, Alaska. They found that the waves in the 1990s were 0.3 seconds faster than those in the 1960s.
 
  • #4
6
0
while we're on the topic of the earth's core, has anyone seen the movie the core? its good for a laugh! there is absolutely no regard for sciencentific evidence in that movie
 
  • #5
4,464
65
Have heard about it. Newton would have pulled his hair out but the movie sort of underlines that the Inner core has a life of its own.
 
  • #6
31
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Tidal forces delux

interforum memo

I have a thought experiment for you. Suppose the earth had a 4 meter hollow sphere exactly in the center. What would the gravitational effects be if you placed a ball bearing in the center of this hollow sphere and dropped it? would it be weightless? Or would you be able to roll it "upside down" (relatively speaking) on the "ceiling." Or would it be pulled apart by tidal forces? hmmm?

Merlin
 
  • #7
4,464
65
Well Merlin,

in the centre of the Earth, all mass is divided equally around you. This means that the sum of all individual gravity vectors is zero. So there is no up or down, just no gravity and the ball bearing would behave exactly as in a spaceship. If you move it off centre a little but, the influence is minimum, changing the total sum only with an infinitemisal small amount.

The pressure in the centre of the Earth is tremendous of course, so it would be a bit hard to dig that hole and get a bearing inside. :wink:
 

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