Why is the value of 'g' greater at the poles than the equator?

We know that earth is not a perfect sphere.

The radius of the earth is more at equator and less at poles.

Now, to understand why the value of g, that is acceleration due to gravity, is more at poles and less at equator we must know the factors on which value of g depends.

Now, relation of g is:

Where, G = Gravitational Constant

M = Mass of Earth

r = Radius of Earth

Now, form the above relation, G and M are constants.

So,

Now, let the radius of poles be and radius at equator be . Also let, the value of g at poles be and let the value of g at equator be.

Now,

And

So,

Now, since, so or.

So, the acceleration due to gravity at poles is more than the acceleration due to gravity at the equator.