Answers
A satellite at altitude h from earth surface is at distance R+h from center of earth where R is radius of earth.
According to Newton's law of universal gravitation, the force of attraction between a satellite with mass m at altitude h is:
Where G = gravitational constant = 6.674x10-11 m3/(kgs2)
R = radius of earth = 6 378 km
M = mass of earth = 5.972 × 1024 kg
m = mass of satellite = 3000 kg, as given in question
A geostationary satellite orbits round earth in 24 hours, thus effectively being stationary w.r.t a certain place on earth surface.
=> The satellite moves through an angle of 2 rad (assuming circular orbit for simplicity of calculation) in 24x3600 seconds
=> angular velocity of satellite:
The centripetal force required to keep the satellite in orbit is given by the formula
When a satellite is in orbit the gravitational force must equal the centripetal force, i.e.
Putting the values of G, M and in above equation,
R+h 422.4x105 m = 42240 km
=> h = (42240 - 6378) km = 35862 km [Ans]
We find that altitude of geostationary satellite is independent of it's mass.
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