loner star
Reciprocating.
The word is oscillation.
back in forth movement is the anwser
if you mean where they rub sideways against eachother then that is called the transform movement.
The back and forth movement is most commonly attributed to oscillations.
they vibrate back and forth.
A
A back-and-forth or reciprocating movement is known as an oscillation. An example would be the motion of a pendulum. Closely related words include flux, undulation, pulsation, cycle, vibration, alternation, and see-saw(ing).
parallax
longitudinal vibration
A vibration.
the movement of the matter that is back and forth, therefore it has physical properties and chemical properties which can be found on the Periodic Table of protons and electrons or the changes of state from solid to liquid to gas and back. science knowledge