A geostationary satellite is an earth-orbiting satellite, placed at an altitude of approximately 35,800 kilometers (22,300 miles) directly over the equator, that revolves in the same direction the earth rotates (west to east).
Application: Geostationary satellites appear to be fixed over one spot above the equator.Receiving and transmitting antennas on the earth do not need to track such a satellite. These antennas can be fixed in place and are much less expensive than tracking antennas. These satellites have revolutionized global communications, television broadcasting and weather forecasting, and have a number of important defense and intelligence applications.
Orbital speed and distance from earth's surface of geostationary satellite
Example: A satellite can be in a geostationary orbit around earth at a distance r from the centre. If the angular velocity of earth about its axis doubles, a satellite can now be in a geostationary orbit around earth if its distance from the centre is related by following what relation?
Solution: for a geostationary satellite, angular velocity of satellite is same as that of earth i.e. ωs=ωe initial ωs=r3GM. if earth's angular velocity is doubled, lets change the radius to R to make it geostationary. So, final ωs=R3GM=2r3GM solving this we get, R=4(31)r