Gravity is slightly lighter on Earth at the equator. This is due to a combination of factors: the Earth's rotation and its non-perfectly spherical shape (it bulges at the equator).
Factors Contributing to Weaker Gravity at the Equator
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Centrifugal Force: The Earth's rotation creates a centrifugal force that acts outwards, opposing gravity. This force is strongest at the equator because the rotational speed is greatest there. Think of it like being on a merry-go-round; you feel pulled outwards.
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Distance from the Earth's Center: The Earth is not a perfect sphere; it's an oblate spheroid, meaning it bulges at the equator. This bulge increases the distance from the Earth's center to the surface at the equator compared to the poles. Since gravitational force decreases with distance, you experience slightly less gravity at the equator.
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Mass Distribution: As noted in the reference, the mass distribution beneath someone at the equator is different from the mass distribution beneath someone at the poles. This difference contributes to a slightly weaker gravitational pull at the equator.
The Result
The combined effect of these factors is a slightly weaker gravitational pull at the equator compared to the poles. The difference is small, but measurable.
