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One force or two forces in Newton's third law?

by TurtleMeister
Tags: force, forces, newton
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Jan26-11, 09:08 AM
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Ah, thanks DH.

I was thinking along the lines of the earth not being perfectly uniform so far as mass goes, so gravity wouldn't point specifically to the centre.

If you imagine for example, the southern hemisphere having a slightly higher mass than the northern then the 'centre point' would be slightly more to the south.

Your explanation seems to cover the issue though.
Jan26-11, 09:10 AM
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Quote Quote by Allen93 View Post
Sorry, I'll clarify. Every object on EARTH, will have a force due to gravity that always point to the center of the Earth's mass.
Read post #18.
Jan26-11, 09:14 AM
P: 12
Quote Quote by D H View Post
Read post #18.
Ah, well my assumption was derived from the notion that Earth was a perfect sphere, which I now understand is wrong. Thank you for clarifying. Would you mind enlightening me on my post under the 'Academic Guidance' section? Thanks.
Jan26-11, 09:57 PM
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Thanks for the reply DH. Your post was informative and interesting. Especially the superposition principle. I will have to read more about that.

Quote Quote by cephron
You might almost say they are the same force, acting bi-directionally*.

*This is a question of semantics, and I don't honestly know if it's considered correct/good practise to call Fwhatever and -Fwhatever "the same force, acting bi-directionally".
Well, that is exactly what I was proposing in my first two posts. But I'm sure it would be considered incorrect by the academic world.

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