( ( Since ( ( the system ) ( is ( in equilibrium ) ) ) ) ( , ( ( ( the ( net force ) ) ( acting ( along ( the y-axis ) ) ) ) ( ( must ( be zero ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (DT the) (NN system)) (VP (VBZ is) (PP (IN in) (NP (NN equilibrium)))))) (, ,) (NP (NP (DT the) (JJ net) (NN force)) (VP (VBG acting) (PP (IN along) (NP (DT the) (NNS y-axis))))) (VP (MD must) (VP (VB be) (NP (CD zero)))) (. .)))
Since the system is in equilibrium, the net force acting along the y-axis must be zero.
(ROOT (S (NP (DT A) (VBG moving) (NN car)) (VP (VBZ is) (VP (VBN said) (S (VP (TO to) (VP (VB be) (PP (IN in) (NP (JJ dynamic) (NN equilibrium))) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBZ is) (NP (CD zero) (JJ net) (NN force)))))))))) (. .)))