( ( ( The pull ) ( of ( ( gravity close ) ( to ( ( ( the ( Earth 's ) ) surface ) ( on ( ( an object ) ( of ( mass m ) ) ) ) ) ) ) ) ) ( ( is ( described ( by ( the ( weight force ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN pull)) (PP (IN of) (NP (NP (NN gravity) (NN close)) (PP (TO to) (NP (NP (NP (DT the) (NN Earth) (POS 's)) (NN surface)) (PP (IN on) (NP (NP (DT an) (NN object)) (PP (IN of) (NP (JJ mass) (NN m)))))))))) (VP (VBZ is) (VP (VBN described) (PP (IN by) (NP (DT the) (NN weight) (NN force))))) (. .)))
The pull of gravity close to the Earth's surface on an object of mass m is described by the weight force .
(ROOT (S (NP (NNP Weight)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (DT the) (NN measure)) (PP (IN of) (NP (NP (DT the) (NN force)) (PP (IN of) (NP (NP (NN gravity)) (VP (VBG pulling) (PRT (RP down)) (PP (IN on) (NP (DT an) (NN object)))))))))))) (. .)))