( ( ( Section 2.1 ) ( Defining ( Motion ( ( Any object ) ( that ( is ( changing ( its position ) ) ) ) ) ) ) ) ( ( is ( said ( to ( be ( in motion ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Section) (CD 2.1)) (VP (VBG Defining) (S (VP (VBG Motion) (NP (NP (DT Any) (NN object)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBG changing) (NP (PRP$ its) (NN position))))))))))) (VP (VBZ is) (VP (VBN said) (S (VP (TO to) (VP (VB be) (PP (IN in) (NP (NN motion)))))))) (. .)))
Section 2.1 Defining Motion Any object that is changing its position is said to be in motion .
(ROOT (S (PP (IN In) (NP (NN science))) (, ,) (NP (NN motion)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NN position))))))) (. .)))