# Fixed Rectangular Coordinate FrameEdit

In this coordinate system, vectors are expressed as an addition of vectors in the x, y, and z direction from a non-rotating origin. Usually is a unit vector in the x direction, is a unit vector in the y direction, and is a unit vector in the z direction.

The position vector, (or ), the velocity vector, , and the acceleration vector, are expressed using rectangular coordinates in the following way:

Note: ,