An object weighs `10 N` at north pole of Earth. In a geostationary satellite distance `7 R` from centre of Earth (of radius `R`), what will be its (a) true weight (b) apparent weight?

Explanation

(a) Given, `mg = 10 N`. The true
weight of body in a satellite at high `h` will be given by
`W_(S) = mg' = mg ((R )/(R + h))^(2) = mg ((R )/(R + 6R))^(2)`
`( :' H = 7 R - R = 6R)`
or `W_(S) = (mg)/(49) = (10)/(49) = 0.2 N`
(b) If g' is the acceleration due to gravity of Earth at the position of satellite and `a` be the acceleration of the satellite, then the apparent weight of body in satellite will be `W_(app) = m(g' - a)`. As satellite is a freely falling body therefore `a = g'`. So
`W_(app) = m(g' - g') = 0`