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1. The problem statement, all variables and given/known data

Derive an expression for the gravitational force between a sphere with mass m and another sphere with mass M and radius R, IF the sphere of mass M has a spherical hollow inside which touches the surface of the sphere and the center of the sphere. The distance between M and m is d (including the radius R and ignoring the radius of m).

2. Relevant equations

F = GMm/r^2

3. The attempt at a solution

I tried to calculate the volume of the sphere with the hollow and I got = 7piR^3/6, but then I don't know what to do. The answer is supposed to be:

F = (GMm/d^2)( 1 - 1/(8(1-R/2d)^2))

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# Homework Help: Hard gravitational force problem

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