Why is the value of g greater at the poles?

The value of acceleration due to gravity (g) is greater at the poles than at the equator due to two main reasons:

1. Shape of the Earth (Oblate Spheroid)

• The Earth is not a perfect sphere; it is slightly flattened at the poles and bulging at the equator.
• As a result, the distance from the center of the Earth to the surface is smaller at the poles than at the equator.
• According to Newton’s law of gravitation, gravity decreases with distance from the center of the Earth, so being closer at the poles increases g.

2. Centrifugal Force Due to Earth’s Rotation

• The Earth rotates about its axis, creating a centrifugal force that acts outward from the axis of rotation.
• This force opposes gravity and is maximum at the equator and zero at the poles.
• Because there is no centrifugal effect at the poles, gravity is slightly stronger there.

Conclusion

• g is greater at the poles because the Earth is closer to its center and there is no opposing centrifugal force due to rotation.