This Demonstration shows how the gravitational force between two spheres depends on their masses and the distance between them. The equation used is , where is the gravitational constant , is the first mass, is the second mass, and is the distance between the centers of the spheres. Use the sliders to change the masses of the objects and the 2D sliders to move the spheres. It is assumed that the spheres do not overlap; otherwise, the force law would become more complicated.