( Buoyancy ( ( is ( ( ( the tendency ) ( of ( ( a fluid ) ( -LRB- ( ( ( gas or ) liquid ) -RRB- ) ) ) ) ) ( to ( ( exert ( an ( upward force ) ) ) ( on ( ( an object ) ( that ( is ( submerged ( in it ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Buoyancy)) (VP (VBZ is) (NP (NP (DT the) (NN tendency)) (PP (IN of) (NP (NP (DT a) (NN fluid)) (PRN (-LRB- -LRB-) (NP (NP (NN gas)) (CC or) (NP (NN liquid))) (-RRB- -RRB-)))) (S (VP (TO to) (VP (VB exert) (NP (DT an) (JJ upward) (NN force)) (PP (IN on) (NP (NP (DT an) (NN object)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN submerged) (PP (IN in) (NP (PRP it)))))))))))))) (. .)))
Buoyancy is the tendency of a fluid (gas or liquid) to exert an upward force on an object that is submerged in it.
(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)))))))))))) (. .)))