Calculating Force of Attraction Between Rocks at a Reduced Distance of 250m

The force between two objects in space follows Newton's Law of Universal Gravitation, which states that the force is proportional to the product of their masses and inversely proportional to the square of the distance between them. Your question doesn't give the important details needed to calculate gravitational force, like the masses of the rocks. But, according to the principles of physics, if the mass of the objects and the distance between the objects doesn't change, the force of attraction will remain constant. Therefore, if the distance between the rocks is reduced to 250 m from its previous unspecified distance, the force would still remain 4 newtons, given that the masses of the rocks stay the same. However, if the rocks were moved closer together or further apart, then the gravitational force would indeed change, following the law of universal gravitation. That being said, the question doesn't provide enough details to make that specific calculation.