( Motion ( ( ( is simply ) ( ( the change ) ( in ( position ( over time ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Motion)) (VP (VBZ is) (ADVP (RB simply)) (NP (NP (DT the) (NN change)) (PP (IN in) (NP (NP (NN position)) (PP (IN over) (NP (NN time))))))) (. .)))
Motion is simply the change in position over time.
(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)))))))) (. .)))