( ( ( ( ( ( Part ( of ( that energy ) ) ) ( increases ( ( the ( kinetic energy ) ) ( of ( the molecules ) ) ) ) ) , ) and ) ( some ( adds ( to ( the ( potential energy ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (NN Part)) (PP (IN of) (NP (DT that) (NN energy)))) (VP (VBZ increases) (NP (NP (DT the) (JJ kinetic) (NN energy)) (PP (IN of) (NP (DT the) (NNS molecules)))))) (, ,) (CC and) (S (NP (DT some)) (VP (VBZ adds) (PP (TO to) (NP (DT the) (JJ potential) (NN energy))))) (. .)))
Part of that energy increases the kinetic energy of the molecules, and some adds to the potential energy .
(ROOT (S (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (DT the) (JJ kinetic) (CC and) (JJ potential) (NNS energies)) (PP (IN of) (NP (NP (DT a) (NN system) (POS 's)) (NNS atoms) (CC and) (NNS molecules)))))) (VP (VBZ is) (VP (VBN called) (NP (JJ internal) (NN energy)))) (. .)))