( ( This car ) ( ( ( ( was ( a ( `` ( pull ( back ( '' car ) ) ) ) ) ) , ) ( using ( elastic ( potential energy ) ) ) ) . ) )
(ROOT (S (NP (DT This) (NN car)) (VP (VBD was) (NP (DT a) (`` ``) (NN pull) (JJ back) ('' '') (NN car)) (, ,) (S (VP (VBG using) (NP (JJ elastic) (JJ potential) (NN energy))))) (. .)))
This car was a &quot;pull back&quot; car, using elastic potential energy.
(ROOT (S (NP (DT The) (ADJP (NN term) (JJ elastic)) (JJ potential) (NN energy)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB describe) (S (NP (JJ potential) (NN energy)) (ADJP (JJ due) (PP (TO to) (NP (NP (DT an) (NN object) (POS 's)) (NN shape)))))))))) (. .)))