( ( Sum ( of ( kinetic ( and ( potential energies ) ) ) ) ) ( ( is conserved ) . ) )
(ROOT (S (NP (NP (NNP Sum)) (PP (IN of) (NP (JJ kinetic) (CC and) (JJ potential) (NNS energies)))) (VP (VBZ is) (VP (VBN conserved))) (. .)))
Sum of kinetic and potential energies is conserved.
(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)))) (. .)))