( ( that ( ( the particles ) ( are elastic ) ) ) ( , ( ( no energy ) ( ( is ( ( ( gained or ) lost ) ( on collision ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN that) (S (NP (DT the) (NNS particles)) (VP (VBP are) (ADJP (JJ elastic))))) (, ,) (NP (DT no) (NN energy)) (VP (VBZ is) (VP (VBN gained) (CC or) (VBN lost) (PP (IN on) (NP (NN collision))))) (. .)))
that the particles are elastic, no energy is gained or lost on collision.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NN gas) (NNS particles)) (VP (VBP collide)))) (, ,) (NP (DT these) (NNS collisions)) (VP (VBP are) (VP (VBN considered) (S (ADJP (JJ elastic))))) (. .)))