( Gravity ( ( is ( ( the force ) ( ( exerted ( by ( ( any object ) ( with mass ) ) ) ) ( on ( ( any ( other object ) ) ( with mass ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Gravity)) (VP (VBZ is) (NP (NP (DT the) (NN force)) (VP (VBN exerted) (PP (IN by) (NP (NP (DT any) (NN object)) (PP (IN with) (NP (NN mass))))) (PP (IN on) (NP (NP (DT any) (JJ other) (NN object)) (PP (IN with) (NP (NN mass)))))))) (. .)))
Gravity is the force exerted by any object with mass on any other object with mass.
(ROOT (S (NP (JJ Bouyant) (NN force)) (VP (VBZ is) (NP (NP (DT the) (JJ upward) (NN force)) (VP (VBN exerted) (PP (IN by) (NP (NP (NNS fluids)) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT any) (NN object)) (, ,) (PP (JJ such) (IN as) (NP (DT a) (NN boat))) (, ,)) (VP (VBZ is) (VP (VBN placed) (PP (IN in) (NP (PRP it)))))))))))) (. .)))