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

Think about a golf ball. If you were microscopic and walking around on that golf ball like it were a planet you’d go uphill and downhill over and over walking in any direction. But why? At any point, draw a line from you to the exact center of that golf ball. Unless that line intersects the surface of that golf ball at 90 degrees, you aren’t on flat ground. The only “level” ground on the golf ball would be at the bottom of each dimple, or on the tops of the ridges in between them. The golf ball has no “north pole” or equator. The direction you walk along the golf ball doesn’t generalize to “always uphill” or “always downhill ” in a certain direction.