The acceleration due to gravity at a height 1 km above the earth is the same as at a depth d below the surface of earth. Then :
Variation in 'g' with height -
gravity at height from surface of earth.
Radius of earth
height above surface
- wherein
Acceleration due to gravity above earth
Since h<<R acceleration due to gravity below earth surface
or
or d = 2h
d = 2 Km
Option 1)
This option is incorrect.
Option 2)
This option is incorrect.
Option 3)
This option is incorrect.
Option 4)
This option is correct.