( ( When ( ( two ( or ( more forces ) ) ) ( act ( on ( an object ) ) ) ) ) ( ( the ( net force ) ) ( ( ( is also ) ( a vector ) ) . ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (CD two) (CC or) (JJR more) (NNS forces)) (VP (VBP act) (PP (IN on) (NP (DT an) (NN object)))))) (NP (DT the) (JJ net) (NN force)) (VP (VBZ is) (ADVP (RB also)) (NP (DT a) (NN vector))) (. .)))
When two or more forces act on an object the net force is also a vector.
(ROOT (S (NP (NP (NNS Objects)) (PP (IN on) (NP (NN earth)))) (VP (VBP have) (NP (NP (CD two) (NNS forces)) (VP (VBG acting) (PP (IN on) (NP (PRP them))) (PP (IN at) (NP (DT all) (NNS times)))))) (. .)))