In classical mechanics, an analytical method applied to a material sphere
to determine the gravitational field at a point outside or inside the sphere.
Newton’s shell theorem states that:
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The gravitational field outside a uniform spherical shell (i.e. a hollow ball) is
the same as if the entire mass of the shell is concentrated at the center of the sphere.
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The gravitational field inside the spherical shell is zero, regardless
of the location within the shell.
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Inside a solid sphere of constant density, the gravitational force varies linearly
with distance from the center, being zero at the center of mass.
For the relativistic generalization of this theorem,
see → Birkhoff’s theorem.
See also: → Newton; → shell;
→ theorem.