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

The idea of North being above South was actually decided by chance. South could also be considered the “top” of the Earth, because it’s arbitrary. The Earth doesn’t really have a top or a bottom.

We define “up” and “down” relative to the direction of gravity, and gravity always pulls towards the center of the Earth. So whether you’re in Antarctica or Brazil, “up” is away from the center from the Earth, and “down” is towards the center.