( ( 2 -RRB- ) ( ( Changing ( ( position and ) ( motion ( -LRB- 4BPS2 ) ) ) ) . ) )
(ROOT (S (LST (LS 2) (-RRB- -RRB-)) (VP (VB Changing) (NP (NP (NN position)) (CC and) (NP (NNP motion) (-LRB- -LRB-) (NNP 4BPS2)))) (. .)))
2) Changing position and motion (4BPS2.
(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)))))))) (. .)))