Its also useful to consider a linearly accelerating chordinate. In such a system, you experience a constant force opposite to the acceleration of chooridanate s

Its also useful to consider a linearly accelerating chordinate. In such a system, you experience a constant force opposite to the acceleration of chooridanate system. That this fictisous force looks just like gravity (for a sufficiently small test particle) leads you directly to the equivelence principle. For practical purposes, fictitious forces are mostly useful because they make working in the corresponding coordinate system easier.