自由落體運動跟質量和緯度的影響

Since part of gravity is used for overcome the centripetal acceleration.
Our earth is rotating, if there is no gravity, we need a rope to tight on the earth or we will fly away. The need of the force to do the rotation is come from gravity.

The need of the centripetal force is mrω, where m is the mass of the object, r is the radius of the circle and ω is the rotating speed (angular speed). We have the same ω on the earth (1 rotation /day), and at different longitude (緯度), the r is different. It is maximum at equator (radius of Earth) and minimum at two poles (zero) as we are rotating through the axis from North Pole to South Pole. The parts gravity used for circular motion by no need on two poles.

There is also the effect of the different of mass distributions, parts on the earth is massive than others, the gravity there is also larger, but that not you want to ask here.