Question

If person A is in a spaceship sitting on the Earth and not accelerating. Person B is in a spaceship with no gravity and accelerating at 9.8m/s^2:

Is there any experiment inside the 2 spaceships that will give different results?

Answer 1

While the laws of motion are the same in all inertial frames(stationary reference frame), in non-inertial frames (accelerating reference frame), they vary from frame to frame depending on the acceleration..

In classical mechanics, it is often possible to explain the motion of bodies in non-inertial reference frames that are accelerating by introducing additional fictitious forces (also called inertial forces, pseudo-forces. and d'Alembert forces) to Newton's second law to which if not added would result in different or worng result. Common examples of this include the Coriolis force and the centrifugal force.