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

If Earth were a perfect sphere, you would never walk uphill or downhill. That perception is entirely based on being internally level, so if you were to walk along a perfect sphere the size of Earth, you would always remain level because the direction in which gravity pulls you is constantly changing. In other words, your distance from the sphere’s center would never change.