I have some doubts on topics related to rotation, so I thought I'd make a single thread rather than multiple ones. 1. Why are the Coriolis and Centrifugal forces "fictitious"? I think I might be getting confused by the terminology, but do they represent physical forces? My lecture notes say they only appear due to choice of coordinate systems. But I want to develop physical understanding rather than mathematical. 2. What exactly do Euler angles represent? My lecture notes describe a three step process of rotations of a rigid body to define them, but I don't really understand much. Any help will be appreciated.