[whatshisface]

In a rotating frame of reference, forces appear in the equations that are proportional to the distance from the center. They are the forces necessary to make an object which is stationary in a non-rotating frame go in a circle in the rotating frame. Those forces do not correspond to springs, gravitating bodies or any physical phenomenon, and are called "fictitious forces." Non-rotating frames of references make those forces go away, and that is why they're special.

[wolverine876]

Thanks!