Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Jon Francis on 19/08/2010 00:49:11
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If it was possible to bore a tunnel to the centre of Earth would gravity be stronger there than on the surface of the planet?
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At the centre of a truly symmetrical sphere the gravitational forces would cancel out: no net force...
Isaac Newton proved the shell theorem saying that:
1. A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point at its centre.
2. If the body is a spherically symmetric shell (i.e. a hollow ball), no gravitational force is exerted by the shell on any object inside, regardless of the object's location within the shell.
3. Inside a solid sphere of constant density the gravitational force varies linearly with distance from the centre, becoming zero at the centre of mass.
http://en.wikipedia.org/wiki/Shell_theorem