Two 15.Kg objects are placed at four different distances from each other. At which distance would the two objects have the strongest gravitational attraction to each other?

The strongest gravitational attraction between the two objects will be experienced when the distance between the two objects is smallest.

Explanation:

According to Newton's law of universal gravitation, the force of attraction between two objects is proportional to the products of their masses and inversely proportional to the square of the distance of separation between the two objects. This attraction between objects is known as gravity and it applies to all objects in the universe.

From the law of universal gravitation, since their is an inverse square relationship between gravitational force and the distance of separation between two interacting objects, an increase in the distance of separation will result in weaker gravitational forces.  For example, if the distance of separation between two objects is increased by a factor of 2, then the force of gravitational attraction is decreased by a factor of 4 (since 2² = 4). However, if the distance of separation between the two objects is decreased by a factor of two, i.e. is halved, then the force of gravitational attraction is increased by a factor of 4.

Thus, the strongest gravitational attraction between the two objects will be experienced when the distance between the two objects is smallest.