Where is gravity greater?

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Offline Jon Francis

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Where is gravity greater?
« on: 19/08/2010 00:49:11 »
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?


Offline RD

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Where is gravity greater?
« Reply #1 on: 19/08/2010 01:31:22 »
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.
« Last Edit: 19/08/2010 01:35:11 by RD »