Question

why Newton's universal law of gravitation include (r)^2 not only r

Answer 1

This is because it contains inverse square law. And we also say that the gravitational force is inversely proportional to the square of distance b/w to mass objects.

Answer 2

Newton's law of universal gravitation. Newton's law of universal gravitation states that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.