Any object being thrown upwards, sooner or later, is on the ground, be it stone, paper, or a simple feather.At the same time, satellite launched into space a half century ago, a space station or a moon continue to rotate in their orbits, as if they are not the force of gravity of our planet.Why is this happening?Why the moon does not threaten to fall on the Earth, and the Earth is not moving toward the Sun?It does not apply to them universal gravitation?
From school physics course, we know that the universal gravitation affects any material body.Then it is logical to assume that there is some force that neutralizes the effect of gravity.This force is called centrifugal.It is easy to feel the effect of tying a thread on one end and a small weight untwisted it in a circle.The greater the speed of rotation of the stronger thread tension, and the slower we rotate the load the greater the probability that it will fall down.
So we are very close to the concept of "escape velocity."In a nutshell it can be described as a speed that allows any object to overcome the attraction of a celestial body.As the heavenly bodies can act planet and its satellite, solar or other system.Space velocity is every object that is moving in its orbit.By the way, the size and shape of the space object's orbit depends on the magnitude and direction of the velocity that the object was at the time of switching off the engine and the altitude at which the event occurred.
escape velocity is of four kinds.The shortest of them - this is the first.This is the lowest rate, which should be at the spacecraft, so that he went into a circular orbit.Its value can be determined by the following formula:
V1 = √μ / r, where
μ - geocentric gravitational constant (μ = 398 603 x 10 (9) m3 / s2);
r - the distance from the start point to the center of the Earth.
Due to the fact that our planet does not form a perfect sphere (at the poles as if it is slightly flattened), the distance from the center to the surface more than to the equator - 6378.1 • 10 (3) m, and at leastpoles - 6356,8 • 10 (3) m. If you take the average value - 6371 • 10 (3) m, we obtain V1 equal to 7.91 km / s.
The more the escape velocity is greater than this value, the more elongated shape will acquire orbit, moving away from the Earth at an increasing distance.At some point it will break orbit, will take the form of a parabola, and the spacecraft go surf the cosmic expanse.In order to leave the planet, the ship must be the escape velocity.It can be calculated by the formula √2μ = V2 / r.For our planet, this figure is 11.2 km / s.
Astronomers have long determined what is the escape velocity, both the first and the second, for each planet in our own system.They are easy to calculate the above formula by replacing the constant μ on the product fM, where M - mass of interest celestial body, and f - the gravitational constant (f = 6,673 x 10 (-11) m3 / (kg x s2).
thirdescape velocity will allow any spacecraft overcome the attraction of the sun and leave their solar system. If you expect her to the sun, you get a value of 42.1 km / s. In order to reach the Earth from orbit near the Sun. need to accelerate to 16.6 km /a.
And finally, the fourth cosmic velocity. With its help, you can overcome the attraction itself the galaxy itself. Its value varies depending on the origin of the galaxy. In our Milky Way, this value is approximately 550 km / s (if you count relativeSun).
