Interaction of bodies in the Universe is defined by their attraction to each other. This attraction is called gravitational interaction. At impact on a body instead of specifying what other body attracts it, usually say that this body is affected by force. Influence of force leads to change of speed of the movement of a body.
What is force?
Force is a physical quantity which value defines quantitative impact of one body on another. In the THIS system force is measured in newtons. The main characteristic of force – quantitative, however matters as well the direction. Force is vector size. Terrestrial gravitation – the most characteristic example of influence of gravitational forces. In the second half of the 17th century the great British physicist Isaac Newton opened the law of universal gravitation which says that force of gravitation depends on the mass of the interacting bodies and distance between them.
Gravity – the phenomenon which people face every second on this phenomenon is constructed all human life. Gravity is called force to which there is an attraction of all bodies Earth. Gravity as at vector size has an orientation: always to the center of the earth. It was by practical consideration established that force of an attraction is directly proportional to the mass of the attracted body. Force of an attraction influences even long distances. There is a hypothesis that during formation of the Galaxy some period of Long possessed the atmosphere as well as Earth now. However because Earth has four times bigger weight, than the Moon, all atmosphere of the Moon passed to Earth under the influence of attraction force.
Types of interaction of bodies
In the nature there is not only a gravitational interaction. Electric and magnetic energy also makes impact on bodies. The simplest electric phenomena occur also in everyday life. For example, when combing the hair often "stick" to a hairbrush, hands, a face – the effect of accumulation of static electric charge is available. In Ancient Greece the experience with the amber rubbed about fur which began to attract after that small objects was known. Amber in Greek "electron" therefore the phenomenon still is called electricity. Pulling, or electricity is a characteristic which objects can possess with different terms. The bodies capable to attract other bodies a long time are called permanent magnets. As well as the electrified subject, a magnet attracts bodies with a certain force. Permanent magnets are known for the properties: obligatory existence of two poles – northern and southern; the fact that force of an attraction is more on poles; fact of an attraction of heteronymic poles and pushing away of the same name. The mother Earth also has powerful magnetic field therefore in turn "subordinates" to himself all existing permanent magnets. In practice it is expressed by the fact that the magnet suspended on a thread surely will be developed so that the poles will point north also the South.