Answer:
Earth's spin on its axis causes the equator to bulge
Explanation:
The Earth is not a perfect sphere but an oblate ellipsoid. The force that holds a planet is gravity. The Earth is rotating on its axis at a speed of 460 m/s at the equator. Due to this reason there is a build up of centrifugal force on the Earth which causes it to expand giving it a bulge.
The Sun and the Moon's gravity causes waves on the surface of large water bodies.
