( ( The ( internal energy ) ) ( ( is ( ( ( the sum ) ( of ( ( the ( kinetic ( and ( potential energy ) ) ) ) ( of ( the ( atom ( amd molecules ) ) ) ) ) ) ) ( that ( ( make up ) ( the system ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ internal) (NN energy)) (VP (VBZ is) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (NP (DT the) (JJ kinetic) (CC and) (JJ potential) (NN energy)) (PP (IN of) (NP (DT the) (NN atom) (NN amd) (NNS molecules))))) (SBAR (WHNP (WDT that)) (S (VP (VBP make) (PRT (RP up)) (NP (DT the) (NN system))))))) (. .)))
The internal energy is the sum of the kinetic and potential energy of the atom amd molecules that make up the system.
(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)))) (. .)))