XVI - XVII centuries, many rightfully call one of the most glorious periods in the history of physics. It was at this time that the foundations were largely laid, without which the further development of this science would be simply unthinkable. Copernicus, Galileo, Kepler did a great job to declare physics as a science that can answer almost any question. Standing apart in a series of discoveries is the law of gravity, the final wording of which belongs to the outstanding English scientist Isaac Newton.
The main significance of this scientist’s work was not in his discovery of the force of gravity - Galileo and Kepler spoke about the existence of this quantity even before Newton, but in the fact that he was the first to prove that both the Earth and outer space act the same forces of interaction between bodies.
Newton in practice confirmed and theoretically substantiated the fact that absolutely all bodies in the Universe, including those located on Earth, interact with each other. This interaction is called gravitational, while the process of universal gravitation itself is called gravity.
This interaction arises between bodies because there is a special kind of matter, unlike others, which in science has been called the gravitational field. This field exists and acts around absolutely any object, while there is no protection against it, since it has the ability to penetrate into any materials that looks like nothing.
The force of universal gravitation, the definition and formulation of which was given by Isaac Newton, is directly dependent on the product of the masses of interacting bodies, and inversely on the square of the distance between these objects. According to Newton, irrefutably confirmed by practical research, the force of universal gravitation is found by the following formula:
F = Mm / r2.
In it, special significance belongs to the gravitational constant G, which is approximately equal to 6.67 * 10-11 (N * m2) / kg2.
The force of universal gravitation, with which bodies are attracted to the Earth, is a special case of Newton's law and is called gravity. In this case, the gravitational constant and the mass of the Earth itself can be neglected, so the formula for finding gravity will look like this:
F = mg.
Here g is nothing more than the acceleration of gravity, the numerical value of which is approximately equal to 9.8 m / s2.
Newton’s law not only explains the processes occurring directly on Earth, it gives an answer to many questions related to the structure of the entire solar system. In particular, the force of universal gravitation between celestial bodies has a decisive influence on the movement of planets in their orbits. A theoretical description of this movement was given by Kepler, however, its justification became possible only after Newton formulated his famous law.
Newton himself connected the phenomena of terrestrial and extraterrestrial gravity with a simple example: when fired from a cannon, the core does not fly directly, but along an arc-shaped trajectory. In this case, with an increase in the charge of gunpowder and the mass of the nucleus, the latter will fly further and further. Finally, if we assume that it is possible to get so much gunpowder and construct such a gun so that the core circulates around the globe, then, having made this movement, it will not stop, but will continue its circular (ellipsoidal) movement, turning into an artificial satellite of the Earth. As a result, the force of universal gravitation is the same in nature both on Earth and in outer space.