Acceleration v Constant Velocity
So until an amount of energy equal to the object's inertia has influenced that object, it's initial position will be maintained?
For example, if the table on which the bottle is positioned in the train were entirely frictionless, the bottle's position would be completely fixed in space and the table would move forward independent of the bottle?
Or in other words, the reason a bottle tips over in the opposite direction of the train's motion is that the friction between the bottom of the bottle and the table means the lower part of the bottle hangs on to the table while the top half's position wouldn't move if not because it's obviously attached to the bottom half.
Not sure I'm properly communicating what I mean, but hopefully you'll understand..