Q.At which place on the Earth's surface is the gravitational acceleration maximum? Why?

[!TLDR] Gravitational acceleration is maximum at the poles, where neither the Earth's rotation nor its equatorial bulge reduces it. [!ANSWER] At the poles, because rotation ca …

Two effects reduce the acceleration due to gravity away from its 'ideal' (non-rotating, perfectly spherical) value: the Earth's rotation, which requires part of the gravitational pull to supply the centripetal force keeping a surface point moving in its daily circle ($g'=g-R\omega^2\cos^2\theta$, maximum reduction at the equator, zero reduction at the poles since points on the axis of rotation do not move in a circle at all), and the Earth's oblate (equator-bulging) shape, which gives the equator a LARGER radius than the poles, further weakening g there since $g\propto1/r^2$. Both effects vanish, or are minimised, at the poles: there is no rotational reduction (poles lie exactly on the rotation axis) and the polar radius is the smallest of any latitude, giving the largest possible value of $GM/ …

Identify the two reducing effects (rotation, oblate shape) and note both are minimised/absent exactly at th …

Attributing the variation to only one of the two effects (rotation OR shape) rather than recognisi …