Question

A geostationary satellite
A. moves faster than the near Earth satellite.
B. has a time period less than that of a near Earth satellite.
C. revolves about the polar axis.
D. is stationary in space.

Answer 1

Hint:Recall the information about the geostationary satellite like its distance from the centre of the Earth, velocity around the Earth, and time period of revolution about the Earth compared to the other near Earth satellite. Hence, check which of the options given in the question are correct and which options are incorrect.

Complete step by step answer:
The orbital velocity of a satellite is given by
\[v = \sqrt {\dfrac{{GM}}{{R + h}}} \]
From the above equation, we can conclude that the orbital velocity of a satellite is inversely proportional to the height of the satellite from the surface of the Earth.

The height of the geostationary satellite is more from the surface of the Earth than a near Earth satellite. Hence, the geostationary satellite should move slower than any near Earth satellite.Therefore, a geostationary satellite does not move faster than the near Earth satellite.Hence, the option A is incorrect.

According to Kepler’s third law, the square of the time period of a satellite or planet around the Sun or any other planet is directly proportional to the cube of its distance from the centre of the Sun or the planet.
\[{T^2} \propto {a^3}\]
The distance of the geostationary satellite is more from the centre of the Earth than a near Earth satellite. Hence, the geostationary satellite should have more time period than any near Earth satellite.Hence, option B is incorrect.

The geostationary satellite is moving around the Earth having the same time period as that of the Earth.Therefore, the geostationary satellite is not stationary in the space but revolving around the Earth.Hence, the option D is incorrect.

The geostationary satellite always moves in the same direction as that of the Earth rotating about its axis that is from west to east which is about the polar axis.Therefore, the geostationary satellite revolves about the polar axis.Thus, option C is correct.

Hence, the correct option is C.

Note: The students should keep in mind that the geostationary satellite is not stationary in space. But the geostationary satellite revolves about the polar axis and if one observes the geostationary satellite from the polar axis, it seems to be stationary. But it is the matter of position from which the satellite is observed. It is not actually stationary in space.