The force of gravity on a 1 kg mass can never be more than 9.8 N(mass), which is the force exerted by the Earth's gravity on a 1 kg mass at sea level. This is because the gravitational force between two objects is directly proportional to the masses of the objects and inversely proportional to the square of the distance between them. Since the Earth is much more massive than any other object on its surface, the gravitational force exerted by the Earth on any object is always greater that the gravitational force exerted by the object on the Earth.