Acceleration due to gravity at a height h above the earth's surface is given by g(1−Re2h)
And acceleration due to gravity at depth d below the earth surface is given by g(1−Red).
As gabove=gbelow
So, g(1−Re2h)=g(1−Red)
⇒Re2h=Red
⇒αh=d
Thus, the value of α=2.