Gravitation — force which holds the Universe. Thanks to it stars, galaxies and planets do not fly in a disorder, and are ordered turned. Gravitation holds us on our native planet, but she prevents spacecrafts to leave Earth. Therefore it is important to know how to overcome gravitation.
Instruction
1. The body flying up comes under influence of several braking forces at once. Gravity attracts it back to the earth, resistance of air prevents to gather speed. To overcome them, the body needs own source of the movement or rather strong initial push.
2. Having enough dispersed, the body can reach the constant speed which it is accepted to call the first space. Moving with it, it becomes the satellite of the planet with which started. To find the size of the first cosmic speed, it is necessary to divide the mass of the planet into its radius, to increase the received number by G — a gravitational constant — and to take a square root. For our Earth it is approximately equal to eight kilometers per second. The satellite of the Moon should gather much more smaller speed — 1.7 km/s. The first cosmic speed is called still elliptic as the orbit of the movement of the satellite which reached it will be an ellipse, in one of focuses of which there is Earth.
3. To leave a planet orbit, the satellite needs speed even more. It call the second space, and a speed more of running away. The third name — the parabolic speed because at it the trajectory of the movement of the satellite from an ellipse turns into the parabola which more and more is moving away from the planet. The second cosmic speed is equal to the first, increased by a root from two. For the satellite of Earth flying at the height of 300 kilometers, the second cosmic speed will be equal to about 11 kilometers per second.
4. Sometimes speak also about the third cosmic speed, necessary to leave borders of the Solar system, and even about the fourth, allowing to overcome gravitation of the Galaxy. However their exact size to call absolutely difficult. Gravitational forces of Earth, the Sun and planets interact very with difficulty which even does not manage to be calculated absolutely precisely now.
5. Than a massivny space body, sizes of the first and second cosmic speed which are necessary that to leave it become that more. And if these speeds it is more than the speed of light, then it means that the space body became a black hole, and cannot overcome its gravitation even light.
6. But it is necessary to overcome gravitation not everywhere. In the Solar system there are areas called Lagrange's points. In these parts the attraction of the Sun and Earth counterbalance each other. Rather easy subject, for example, the spacecraft, can "hang" there in space, remaining motionless on the relation both to Earth, and to the Sun. It is very convenient for researches of our star, and in the future, perhaps, and for creation of "transshipment terminals" for studying the Solar system.
7. Lagrange's points only five. Three of them are on the straight line connecting the Sun and Earth: one beyond the Sun, the second between it and Earth, the third behind our planet. Other two points are located almost in Earth orbit, "ahead of" and "behind" the planet.