Two spheres of masses m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be

Gravitational force is one of the fundamental forces of nature that acts between two masses and depends only on the masses and the distance between them. It is governed by Newton’s law of gravitation, which states that the gravitational force is proportional to the product of the two masses and inversely proportional to the square of the distance between their centers.

When two spheres of masses m and M are kept in air, the gravitational force between them is F. It might appear that, if the space surrounding these masses be filled with a liquid of specific gravity 3, then the gravitational force might become affected. Gravitational force does not depend upon the medium surrounding the masses. It’s the universal force, independent on whether the masses are air, water, or even any other medium.

The specific gravity of the liquid affects only forces of a buoyant nature- that are independent of the actual gravitational attraction. As for buoyancy, it indeed determines an apparent weight, that’s different from the real gravitational attracting each other. Hence for such masses, where one’s space is filled with fluid with specific gravity 3, will not change the amount of gravitational force between it – it remains to be just F.