Geostationary satellite orbits around the earth in a circular orbit of radius 36000 km. Then the time period of a spy satellite orbiting a few hundred kilometres above the earth's surface `(R_("earth")=6400 km)` will be approximately be

Options

A. `1//2` hr
B. 1 hr
C. 2 hr
D. 4 hr.

Answer

C

Explanation

`(T_(2))/(T_(1))=((R_(2))/(R_(1)))^((3)/(2)) rArr T_(2)=24((6400)/(36000))^((3)/(2))=1.7` hours.
For spy satellite h is slightly greater than `R therefore T=2hr`.
So correct choice is (c ).