1. The problem statement, all variables and given/known data 23) A person weighs less at the equator than at the poles. The main reason for this has to do with A) the spin of the Earth. B) the shape of the Earth. C) both the spin of the Earth and the shape of the Earth. D) the influence of the sun, moon, and all the planets. E) the law of action and reaction. Answer: C I understand how shape affects it, but I am puzzled about the effect of the spin.