Two small lead balls of masses and are fixed a distance apart on a laboratory bench. A student moves the larger mass toward the smaller mass so the distance is now only . After the mass was moved, by what factor did the gravitational force between the lead balls change?

The gravitational force between two objects is . What would be the force of gravity between them if the mass of one of the objects is tripled and the distance between them is doubled?

Which of these equations is the universal gravitational equation?