Please help me with the following problems!! Four 9.5 kg spheres are located at the corners of a squareof side .60m. calculate the magnitude and direction fo the total gravitational force exerted on one sphere by the other three. *I think I'm supposed to use the forumula : F= G(m1)(m2)/r^2 . where I substitue m1 for the mass of one sphere, and m2 for the mass of the other 2 spheres. I put in .60 for r. What am I doing wrong, I should be getting 3.2*10^8 but I dont! Every few hundred years most of the planets line up on the same side of the sun. Calculte the total force on the EArth due to Venus, Juipter and saturn assuming all four planets are in a line. The amsses are Mv=.0815M(of earth), Mj=318Mass(of earth), Ms=95.1M(of earth), and their mean distances from the sun are 108, 150 ,778 and 1430 million km, respectively. What fraction of the sun's force on the Earth is this? Any hints as to how to even begin to do this one?