Two identical spheres are placed in contact with each other. The force of gravitation between the spheres will be proportional to ( R = radius of each sphere)

Two identical solid copper sphere of radius R are placed in contact with each other. The gravitational force between them is proportional to.

Two identical solid copper spheres of radius R placed in contact with each other. The gravitational attracton between them is proportional to

Two identical solid copper spheres of radius R placed in contact with each other. The gravitational attracton between them is proportional to

Two metal spheres of same material and each of radius r are in contact with each other. The gravitational force of attraction between the spheres is proportional to