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Old 2007-09-15, 14:34   #1
davieddy
 
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"Lucan"
Dec 2006
England

145128 Posts
Default Using geometry to avoid calculus

Show that a spherical shell of mass M attracts an external mass m as would a point mass M at its centre.

The simplest argument uses Gauss' theorem about flux, and symmetry.
To show it directly we sum the force exerted by each element of area in the shell on m.
How would you do this?

David

PS assume Newton's law of gravitation.

Last fiddled with by davieddy on 2007-09-15 at 15:13
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