( It ( ( ( does this ) ( by ( reporting ( ( how much ) ( upward ( force ( it ( needs ( to ( exert ( on ( an ( object ( to ( ( keep ( that object ) ) ( from accelerating ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ does) (NP (DT this)) (PP (IN by) (S (VP (VBG reporting) (SBAR (WHNP (WRB how) (JJ much)) (S (ADVP (RB upward)) (VP (VBP force) (SBAR (S (NP (PRP it)) (VP (VBZ needs) (S (VP (TO to) (VP (VB exert) (PP (IN on) (NP (DT an) (NN object) (S (VP (TO to) (VP (VB keep) (NP (DT that) (NN object)) (PP (IN from) (NP (VBG accelerating))))))))))))))))))))) (. .)))
It does this by reporting how much upward force it needs to exert on an object to keep that object from accelerating.
(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)))))))))))) (. .)))