This consists of an oriented straight line in  which  motion occurs, called the axis, and a point that we accept is at rest, called the origin of the reference frame.

Consiste nunha liña recta na que ocorre o movemento, chamada o eixe, e un punto que consideramos en repouso, chamado a orixe do marco de referencia.

Distance from the object to the origin of the reference frame. Its sign depends on the side of the axis it is on.

Distancia dende o obxecto ata a orixe do marco de referencia. O seu signo  depende do lado no que estea o eixe.

Difference between any two positions.

A body moves when it varies its position in regard to the origin of the reference frame. It is called moveable.

Un corpo móvese cando cambia a súa posición respecto á orixe do marco de referencia. Chámase móbil.