on a body that moves around the earth, there is only one force - a force of gravity of our planet.The object in this case will move unevenly and neravnouskorenno.This is because the acceleration and speed in this case does not satisfy the conditions of uniform / uniformly accelerated motion with constant direction and magnitude of the velocity / acceleration.These two vectors (velocity and acceleration) as it moves in its orbit will change all the time direction.Therefore, such a move is sometimes called motion at a constant speed in a circular orbit
first space - the speed you want to give the body in order to bring it into a circular orbit.At the same time it will be like a satellite.In other words, the first space - speed, reaching that body moving over the surface of the Earth will not fall on it, and will continue to move in its orbit.
For the convenience of calculations, you can see this movement as taking place in a non-inertial frame of reference.Then the body in orbit can be considered in a state of rest, since it will operate two forces: centrifugal and gravity.Therefore, the escape velocity is calculated based on the consideration of the equality of these two forces.
calculated it on a certain formula, which takes into account the mass of the planet, the mass of the body, the gravitational constant.Substituting the known values in a certain formula obtained: the first space speed - 7.9 kilometers per second.
In addition, there are the first cosmic velocity of the second and third.Each of the space velocity is calculated according to certain formulas and interpreted physically as the rate at which any body that runs from the surface of planet Earth is either artificial satellite (this happens when the first cosmic velocity), or goes out of Earth's gravitational field (this occurs when theescape velocity), or will leave the solar system, overcoming the pull of the Sun (this happens when the third cosmic speed).
spacecraft, typing speed, equal to 11.18 kilometers per second (second space), can fly in the direction of the planets in the solar system: Venus, Mars, Mercury, Saturn, Jupiter, Neptune, Uranus.But in order to achieve any of them, it is necessary to consider their movement.
Previously, scientists believed that the movements of the planets, and even going in a circle.And only Kepler found this form of their orbits and the law on which the change speed of the celestial bodies as they revolve around the sun.
concept of escape velocity (the first, second or third) is used in the calculation of the motion of artificial body in the gravitational field of any planet and its natural satellite, and the sun.So it is possible to determine the speed of the space, such as the Moon, Venus, Mercury and other celestial bodies.These rates must be calculated using formulas that take into account the mass of the celestial body, the gravitational force that must be overcome
third space can be determined based on the condition that the spacecraft should be in relation to the Sun, the parabolic trajectory of movement.For this, during the startup at the surface of the Earth at a height of about two hundred kilometers its speed should be equal to about 16.6 kilometers per second.
Accordingly cosmic speed can be calculated also for the surfaces of other planets and their satellites.For example, the Moon will be the first space of 1.68 kilometers per second, the second - 2.38 kilometers per second.Escape velocity for Mars and Venus, respectively, equal to 5.0 kilometers per second and 10.4 kilometers per second.
