Physics, Astronomy & Cosmology / Re: If you hollowed out the earth and left a shell, how would an entity get around« on: 02/06/2016 22:39:33 »
Quote from: impyre
I imagine it depends on the thickness of the shell. If it's thick enough then you'd get some light gravity pulling you toward the shell itselfThis calculation was done my first-year physics class at university.
As I recall, the gravitational attraction towards the center of a spherical object is determined by the amount of mass between you and the center, and is not affected by the amount of mass at a greater radius than the observer.
So in this example, the entire volume inside the sphere would experience microgravity.
You would not be pulled towards the nearby shell, because it is exactly counterbalanced by the pull of the larger amount of the shell which is on the other side of you (but farther away).
Apparently, Isaac Newton deduced this result - but then he had to invent new physics (universal law of gravitation) and a whole new branch of mathematics (differential equations) to do the calculations. A bright cookie.
Quote from: Alan McDougall
I did say the shell was 2,000 kilometers thick?The result is independent of the thickness of the shell.
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