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A comment on How to destroy the Earth (completely). Parent comment

Re:How to destroy the Earth (completely) by merraksh on Sunday June 20, 2010 @10:29PM (#1447706)
In the perfectly spherical earth hypothesis, being the center of mass in the black hole, wouldn't there be a resulting force towards the center, although very small?

[EDIT] Hmm I think I see the point. The resulting force would be proportional to the ratio (black hole mass / earth's mass). Very small indeed.

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Re:How to destroy the Earth (completely) by vecter on Sunday June 20, 2010 @10:38PM (#1447727)
No, that's irrelevant: http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/sphshel...
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Re:How to destroy the Earth (completely) by ars on Sunday June 20, 2010 @10:47PM (#1447755)
That's for a hollow shell.

For a solid sphere, there is always force toward the center. (And the closer to the center the lower the force, reaching 0 in the middle.)

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Re:How to destroy the Earth (completely) by jules on Monday June 21, 2010 @08:31AM (#1448583)
No, the force is EXACTLY zero, not just very small.
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Re:How to destroy the Earth (completely) by ars on Monday June 21, 2010 @10:11AM (#1448818)
Inside the cave yes, but not when it's inside the solid mass of the earth. Inside a solid sphere the force is toward the center.
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Re:How to destroy the Earth (completely) by jules on Monday June 21, 2010 @04:41PM (#1450015)
Yes, but we're talking about the situation where there is a cave?
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