Time period of the satellite: The distance covered by the satellite during one rotation in its orbit is equal to 2π(RE + h) and time taken for it is the time period, T. Then,
Squaring both sides of the equation (2) we get
Equation (3) implies that a satellite orbiting the Earth has the same relation between time and distance as that of Kepler’s law of planetary motion. For a satellite orbiting near the surface of the Earth, h is negligible compared to the radius of the Earth RE . Then,
By substituting the values of RE = 6.4 × 106 m and g = 9.8ms-2 , the orbital time period is obtained as T ≅ 85 minutes.
