Acceleration due to gravity

The acceleration due to gravity varies from the poles to the equator, mainly due to two factors: Earth’s rotation and its shape. Earth is not a perfect sphere; it is an oblate spheroid, meaning it is slightly flattened at the poles and bulging at the equator. Consequently, the distance from the center of the Earth to the surface is greater at the equator than at the poles.

The force of gravity is strongest at the poles where the Earth’s rotation is least effective. This is because the gravitational force varies directly with the mass of the Earth and inversely with the square of the distance from the center of the Earth. Conversely, at the equator, the centrifugal force created by the Earth’s rotation opposes the force of gravity, thus reducing the effective acceleration due to gravity. This centrifugal force is greatest at the equator because the linear speed due to rotation is the highest at the equator.

Because of this, the acceleration due to gravity decreases from about 9.83 m/s² at the poles to about 9.78 m/s² at the equator. This variation is important in many applications such as navigation, satellite positioning, and understanding the behavior of objects in different gravitational fields.