Question

why gravitational force is more on poles as compared to gravitational force on equator

Answer 1

because earth is slightly flat shape.the shape of earth is not perfect sphere ,it is likely orange.

Answer 2

Because the Earth is not a sphere it is somewhat elliptical and hence the radius of Earth is grater at the equator and smaller at the poles and as we know Gravitational force is indirectly proportional to the square of Distance between the centre of the objects. Therefore since the Distance decreases at poles the force increases.