( ( ( Weight , ) ( ( The Force ) ( of Gravity ) ) ) . )
(ROOT (NP (NP (NNP Weight)) (, ,) (NP (NP (DT The) (NNP Force)) (PP (IN of) (NP (NNP Gravity)))) (. .)))
Weight, The Force of Gravity.
(ROOT (S (NP (NNP Weight)) (VP (VBZ is) (NP (NP (DT the) (NN force)) (PP (IN of) (NP (NN gravity))))) (. .)))