if all motion is relative, how do we know the Earth isn’t stationary with everything else in the Universe rotating around us, albeit in a right weird and in uniform way.

Question

if all motion is relative, how do we know the Earth isn’t stationary with everything else in the Universe rotating around us, albeit in a right weird and in uniform way.

In: Physics

Answer 1

All motion is **not** relative, only motion at constant velocity, called an inertial frame of reference. Velocity includes direction, so if you are rotating or orbiting another object, your velocity is constantly changing and are not in an inertial frame of reference.