If we throw a stone with some speed in a horizontal direction, it follows a curved path as it falls to the ground. If the stone is thrown with a higher speed it follows a path of bigger radius as it falls. We thus conclude that the higher the speed of the stone, the greater the radius of the curved path. If somehow we could throw the stone with such tremendous speed that the radius of its path became a little greater than the radius of the earth, the stone would fall around the earth, rather than on it. This is the principle of an artificial satellite.

In the case of a satellite, the centripetal force is provided by the gravitational pull of the earth. We can calculate the speed of a satellite at a distance r from the centre of the earth by equating the centripetal force with the gravitational force. Thus if m is the mass of the satellite and g be the acceleration due to gravity, we have

F (centripetal) = F (gravitational)

mv2 / r = mg.v2 = rg

In the case of a satellite, the centripetal force is provided by the gravitational pull of the earth. We can calculate the speed of a satellite at a distance r from the centre of the earth by equating the centripetal force with the gravitational force. Thus if m is the mass of the satellite and g be the acceleration due to gravity, we have

F (centripetal) = F (gravitational)

mv2 / r = mg.v2 = rg