Q.
The weight of an object at the equator is the same as its weight at height h above the pole. If ω is the rotational speed of Earth, then the value of h is
g=gp−ω2Rcos2λ
At equator, λ=0 ⇒geq=gp−ω2Rcos20=gp−ω2⋅R
Now, g′ above the pole is g′=gp(1−R2h)
As geq=g′ gp−ω2R=gp(1−R2h)
So, ω2R=R2h⋅gp ⇒h=2gpω2⋅R2=2gω2⋅R2