physics 9th class satellites, GPS, communication satellite,geostationary...

SATELLITE

An object that revolves around the planet
is called a satellite.

Natural
satellite

Natural object which revolve around some
planets is called natural satellite

 i.e The
moon revolves around the Earth so moon is a natural satellite of the Earth

Artificial
Satellite

Scientists have sent many objects into
space. Some of these objects revolve around the Earth. These are called
artificial satellites. Most of the artificial satellites, orbiting around the
Earth are used for communication purposes.

GPS

 Global Positioning System (GPS) is a
satellites navigation system. It helps us to find the exact position of an
object anywhere on the land, on the sea or in the air. GPS consists of 24
Earth satellites. These satellites revolve around the Earth twice a day with a
speed of 3.87
km s-1.

Geostationary
satellite

 Geostationary satellites orbit around the
earth at a altitude  of 42300
km. their
velocity with respect to earth is zero so they appear stationary with respect
to earth so they are known as Geostationary satellites

Geostationary satellites are used for
communication