( ( ( The magnitude ) ( of ( the ( velocity vector ) ) ) ) ( ( ( is merely ) ( ( the ( instantaneous speed ) ) ( of ( the object ) ) ) ) ; ) )
(ROOT (S (NP (NP (DT The) (NN magnitude)) (PP (IN of) (NP (DT the) (NN velocity) (NN vector)))) (VP (VBZ is) (ADVP (RB merely)) (NP (NP (DT the) (JJ instantaneous) (NN speed)) (PP (IN of) (NP (DT the) (NN object))))) (: ;)))
The magnitude of the velocity vector is merely the instantaneous speed of the object;
(ROOT (S (NP (JJ Instantaneous) (NN velocity)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT the) (NN velocity)) (PP (IN of) (NP (DT the) (NN object))))) (PP (IN at) (NP (DT a) (VBN given) (NN moment))))) (. .)))