The force is directly proportional to the product of the masses or charges; the force is directed along the line that connects the two particles. Differences: Newton's law includes a minus sign while Coulomb's law does not; the gravitational constant G is many orders of magnitude smaller than the Coulomb constant k. The force varies as1/r^2the force is directly proportional to the product of the masses or charges; the force is directed along the line that connects the two particles. Differences: Newton's law includes a minus sign while Coulomb's law does not; like charges repel, like masses attract; the gravitational constant G is many orders of magnitude smaller than the Coulomb constant k.