SATELLITES

The objects moving around a planet are called the satellites of that planet. The moon moves around the earth hence moon is a satellite of the earth. The moon is a natural satellite of the earth. The centripetal force must be provided for moon to move around the earth . Here the necessary centripetal force is provided by the gravitational force between the moon and the earth.
In the same way by providing necessary centripetal force by by the gravitational force between the earth and the object it is possible to make it to move around the earth . These days there are very large numbers of human beings made satellites i.e. artificial satellite moving around the earth in different orbit saving different purpose,such as transmission of tv and radio programs for the telecommunication purposes etc.
LAUNCHING SATELLITE'S:
When satellite are made to move away from the earth's gravitational field the minimum velocity required is 11.3k/s or 40320 km/hr. Using a single stage rocket it is not possible to have so much velocity. Hence for launching satellites multistage rockets are used. Generally for such purposes 3-stage rockets satellites is always kept at the rckets are used.
In the rockets satellites is always kept at the top of the third stage . During launching of the rockets the burnt fuels comes out from the nozzle of the rocket, Then according to the third law of motion the opposite reaction that exceeds rockets weight lift and moves the rocket in upward direction. The rocket accelerates upwards and rises vertically upward so that it passes through the denser atmosphere with least time. Then first stage of the second stage makes the rocket to move with high velocity. After moving through certain distance attaining the height speed the second stage of the rocket also detached and falls back. Using the final third stage of the rocket the satellites is turned in the horizontal direction and is given proper speed for the satellite so that it remains on the orbit.Then the satellite moves around the earth in a closed orbit.