Mountain pull. a large mountain can slightly affect the direction of ""down"" as determined by a plumb line. assume that we can model a mountain as a sphere of radius r = 2.00 km and density (mass per unit volume) 2.6 × 103 kg/m3. assume also that we hang a 0.750m plumb line at a distance of 3r from the sphere's center and such that the sphere pulls horizontally on th