1. The problem statement, all variables and given/known data Two fully equal sphere's of lead are placed next to each other so that the gravitational force between sums up to 10N. Calculate mass and radius of the two sphere's. F=10N , ρlead=11300kg/m2 2. Relevant equations F=gm, F=GMm/r2 , V=4πr3/3 , ρ=m/V 3. The attempt at a solution This has bugged me for quite some time now. With only gravitational force and density known, any attempt i do to calculate either mass or radius end's up with either two unknown variables or the wrong answer. I am missing something crusial. Please Point me in the right direction :).