( This ( ( is ( ( ( the ( resistance force ) ) ( -LRB- ( ( directed upward ) -RRB- ) ) ) ( exerted ( by ( the water ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (NP (NP (DT the) (NN resistance) (NN force)) (PRN (-LRB- -LRB-) (VP (VBN directed) (ADVP (RB upward))) (-RRB- -RRB-)) (VP (VBN exerted) (PP (IN by) (NP (DT the) (NN water)))))) (. .)))
This is the resistance force (directed upward) exerted by the water.
(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)))))))))))) (. .)))