( ( ( ( ( Motion ( is ( ( defined ( as ( ( the change ) ( of position ) ) ) ) ( over time ) ) ) ) , ) but ) ( ( both ( of ( ( ( ( these quantities ) , ) ( ( position and ) time ) ) , ) ) ) ( ( are not ) ( defined ( within ( the system ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Motion)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT the) (NN change)) (PP (IN of) (NP (NN position))))) (PP (IN over) (NP (NN time)))))) (, ,) (CC but) (S (NP (NP (DT both)) (PP (IN of) (NP (NP (DT these) (NNS quantities)) (, ,) (NP (NN position) (CC and) (NN time)) (, ,)))) (VP (VBP are) (RB not) (VP (VBN defined) (PP (IN within) (NP (DT the) (NN system)))))) (. .)))
Motion is defined as the change of position over time, but both of these quantities, position and time, are not defined within the system.
(ROOT (S (NP (NNP Motion)) (VP (MD can) (VP (VB be) (VP (VBN defined) (ADVP (RB simply)) (PP (IN as) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NN position)))))))) (. .)))