# Sensing fictitious forces

I need to clarify my understanding of fictitious forces and our sensation of them. It is my understanding that fictitious forces are terms added when Newton's laws are resolved in accelerating reference frames.

And I often read that the force we expecrience upon sudden acceleration in a car say, is a fictitious force.

I am now going to present a thought experiment to consider this statement: I am standing on top of a tall, blacked-out, train by an open 'sunroof'. At the moment the train accelerates rapidly, I jump from the roof, through the 'sunroof' and I then see my self apparently accelerating backwards. A fictitious force would be required to describe my apparent acceleration from the reference frame of the train, but I do not think I would feel any force during this event. So what is the distinction between the sensed fictitious force in the above car scenario, and the unsensed one in the train scenario.

Is a fictitious force only felt when you are attached to the accelerating reference frame you are doing your physics in as it is only in this case that you actually accelerate and your inertia creates the force sensation?