The position
the velocity
and the acceleration
are defined by:
The following holds:

When the acceleration is constant this gives:
For the unit vectors in a direction perpendicular to the orbit
and parallel to it
holds:
For the curvature k and the radius of curvature
holds:
Polar coordinates
Polar coordinates are defined by:
. So, for the unit coordinate vectors holds:
The velocity and the acceleration are derived from: