( ( As ( they fall ) ) ( this ( ( is ( converted ( into ( ( ( ( energy ( of motion ) ) , ) or ) ( kinetic energy ) ) ) ) ) . ) ) )
(ROOT (S (SBAR (IN As) (S (NP (PRP they)) (VP (VBP fall)))) (NP (DT this)) (VP (VBZ is) (VP (VBN converted) (PP (IN into) (NP (NP (NP (NN energy)) (PP (IN of) (NP (NN motion)))) (, ,) (CC or) (NP (JJ kinetic) (NN energy)))))) (. .)))
As they fall this is converted into energy of motion, or kinetic energy.
(ROOT (S (NP (JJ Kinetic) (NN energy)) (VP (VBZ is) (NP (NP (DT the) (NN energy)) (PP (IN of) (NP (NN motion))))) (. .)))
Kinetic energy is the energy of motion.