Given radius of earth ‘R’ and length of a day ‘T’ the height of a geostationary satellite is [G – Gravitational constant, M – Mass of earth]
Correct Answer :
(GMT²/4π²)⁰.³³ - R
Solution :
The correct option is (GMT²/4π²)⁰.³³ - R.
To find the height of a geostationary satellite, we need to balance the gravitational force acting on the satellite with the centripetal force required to keep it in a circular orbit around the Earth.
Let:
- be the mass of the Earth.
- be the radius of the Earth.
- be the height of the geostationary satellite above the Earth's surface.
- be the orbital radius of the satellite from the center of the Earth, such that:
- be the mass of the satellite.
- be the time period of the satellite's rotation, which is equal to the length of a day (since it is a geostationary satellite).
The gravitational force between the Earth and the satellite is given by Newton's law of gravitation:
The centripetal force required to keep the satellite in orbit is:
Here, the angular velocity is related to the time period by the relation:
Equating the gravitational force to the centripetal force:
Canceling the mass of the satellite from both sides and simplifying:
Rearranging the equation to solve for the orbital radius :
Taking the cube root of both sides (which is equivalent to raising to the power of 1/3, or approximately 0.33):
Since the height of the satellite above the surface is , we substitute the expression for :
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