A geo-stationary stellite orbits around the earth in a circular orbit of radius 36,000km. Then, the time period of a spy stellite orbitting a few hundred km above the earth's surface `(R_(earth) = 6400km)` will approximately be

Explanation

Here, `T_(G) = 24 h, R_(G) = 36000 km , T_(S) = ?`
`R_(S) ~~6400 km`
`T_(S) = T_(G) ((R_(S))/(R_(G)))^(3//2) = 24 ((6400)/(36000))^(3//2) = 1.7 h`
For the spy satellite, `R` is slightly greater than radius of Earth, so `T_(S) gt 1.7 h`. Hence `T_(S) ~~2h`