( This ( ( stored ( energy ( is ( called ( potential energy ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBD stored) (SBAR (S (NP (NN energy)) (VP (VBZ is) (VP (VBN called) (NP (JJ potential) (NN energy))))))) (. .)))
This stored energy is   called potential energy.
(ROOT (S (NP (JJ Potential) (NN energy) (NN energy)) (VP (VBZ is) (VP (VBN stored) (PP (IN in) (NP (DT a) (NN person) (CC or) (NN object))))) (. .)))