If the earth is a sphere, as we walk on its surface, are we constantly walking imperceptibly uphill, or imperceptibly downhill? Or something else?

Question

My family members say you’re walking downhill from the north pole to the equator, and uphill going the opposite way, but that doesn’t make sense, because you’re still walking along an arc on the sphere. I’ve stared and stared and stared at this baseball in my hand, but can’t figure it out.

In: Physics

Answer 1

On a perfect sphere, your center of mass isn’t moving up or down no matter how far you walk. “Downhill” doesn’t exist from your point of view, essentially.