( ( Internal energy ) ( ( ( ( is ( equal ( to ( ( the sum ) ( of ( ( the ( kinetic energy ) ) ( of ( ( the ( random motion ) ) ( of molecules ) ) ) ) ) ) ) ) ) ( relative ( to ( ( the center ) ( of ( ( ( mass ( of bodies ) ) and ) ( ( the ( potential energies ) ) ( of ( ( the interaction ) ( of molecules ) ) ) ) ) ) ) ) ) ) ( with ( one another ) ) ) . ) )
(ROOT (S (NP (NNP Internal) (NN energy)) (VP (VBZ is) (ADJP (JJ equal) (PP (TO to) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (NP (DT the) (JJ kinetic) (NN energy)) (PP (IN of) (NP (NP (DT the) (JJ random) (NN motion)) (PP (IN of) (NP (NNS molecules)))))))))) (ADVP (JJ relative) (PP (TO to) (NP (NP (DT the) (NN center)) (PP (IN of) (NP (NP (NP (NN mass)) (PP (IN of) (NP (NNS bodies)))) (CC and) (NP (NP (DT the) (JJ potential) (NNS energies)) (PP (IN of) (NP (NP (DT the) (NN interaction)) (PP (IN of) (NP (NNS molecules))))))))))) (PP (IN with) (NP (CD one) (DT another)))) (. .)))
Internal energy is equal to the sum of the kinetic energy of the random motion of molecules relative to the center of mass of bodies and the potential energies of the interaction of molecules with one another.
(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)))) (. .)))