# Is it always possible for an observer to realize to be in a non-inertial frame?

Galilean relativity principle states that two frames moving with uniform linear motion cannot be distinguished. But is it always possible to realize to be in a non-inertial frame?

In a rotating frame it is surely possible for the observer to realize that because of Coriolis force, which cannot be explained, even supposing the presence of a source of force somewhere.

But in a frame moving linearly, for istance, with acceleration $A$? Coriolis term is not present, so what is the way for the observer in the frame to realize that he is in a non-inertial frame?

• Newton's laws don't apply in non-inertial frames. If you let go of a ball and it falls to the floor or drifts to the ceiling, there is a non-inertial acceleration term that wouldn't be there if you were in an inertial system. Commented Apr 6, 2016 at 21:36
• @CuriousOne: this should be an answer, because it is.
– user107153
Commented Apr 6, 2016 at 23:50
• The most easiest: watch whether all bodies, small or large, are having same acceleration.
– user36790
Commented Apr 7, 2016 at 10:03