Final answer:
The gravitational force increases with the mass of interacting objects due to the direct proportionality between gravity and the product of masses as described by Newton's law of universal gravitation. The increase in gravity also affects the density and size of massive objects by compacting materials together.
Step-by-step explanation:
As the mass of the interacting objects increases, the gravity increases. This is explained by Newton's law of universal gravitation, which states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Therefore, an increase in mass leads to a greater gravitational pull between objects, assuming the distance between them remains constant. Additionally, when mass increases, the gravity of a planet can cause compressible materials to become more tightly packed, potentially decreasing the size of the object even as mass increases. This reinforces the fact that gravity is a fundamental property of mass, and any two objects with mass will exert a gravitational pull on one another, regardless of their distance, although the force weakens significantly with increasing distance.