Question

How far above the surface of Earth do you need to go for g to be reduced to 0.5 of its value on the surface of Earth?

Answer 1

g (at surface)=GM/R^2 (where, R= Radius of earth- 6400 km, M =mass of earth)
g (at height r) =GM/r^2
But GM/r^2=1/2*GM/R^2
Or r=R*sqrt(2)
=6400*sqrt(2)