Question

Find the depth from the surface of earth at which weight of a body of mass m will be reduced by 18% of it's weight on the surface

Answer 1

For any depth d the change in acc. can be calculated by the formula :
G’/g = 1 - d/r
Where r is the radius of the earth and G’ is the change in acc.
So , 18/100 = 1 - d/r
1 - 18/100 = d/r
41/50 = d/r
41/50 . r = d
As we know that radius of earth is equal to 6400km
So 41/50.6400 = d = 5648 km