1. The problem statement, all variables and given/known data is the potential in the center of a solid 3d sphere having uniform mass density and a total mass of m (which is constant), which is gravitating according to an inverse 10th power law, inversly proportional to the square of its radius? this isnt really homework but I figured people would think it was anyway. (this concerns nuclear forces and potentials). the number 10 has no special significance. 2. Relevant equations potential at point x = energy released in moving from infinty to point x. energy=force * distance 3. The attempt at a solution the calculus is far beyond me but intuition and symmetry tell me that it must be. obviously the field is negligible everywhere except very close to the surface of the sphere. if the radius is cut in half then the density would be 8 times as great. so we can think of this as making the field everywhere 8 times as great but halving the distances involved so the potential would be 8/2 times as great.