Gravity Force Calculator
Newton’s law of universal gravitation: any two bodies are attracted to each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
.Calculation of gravity (the force of attraction of two bodies)
Consequences of the law of universal gravitation
Since the mass of the Earth is constant, the weight of the body will change in direct
proportion to its mass and inversely proportional to the square
distances from the center of the Earth. Therefore, two lead balls of the same diameter at the same distance from the center of the Earth should have the same weight. Since the Earth is somewhat flattened at the poles, the body must weigh somewhat more at the pole than at the equator or at some intermediate latitude. Is this really the case? Experience shows that a ball or other body weighing 16 kg at sea level at 45° latitude weighs 16.2 kg at the pole and 15.9 kg at the equator. All these facts confirm Newton’s formula about the law of universal gravitation. 
G – the constant value and is determined experimentally and is equal to: G = 6.67 × 10-11 N × m2 / kg2
The law of universal gravitation is that all bodies are attracted to each other. And this attraction is mutual.