( ( that ( ( ( the frequency ) ( of waves ) ) ( is ( ( the number ) ( of ( waves ( that ( go ( past ( ( a ( fixed point ) ) ( in ( ( a period ) ( of time ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (FRAG (SBAR (IN that) (S (NP (NP (DT the) (NN frequency)) (PP (IN of) (NP (NNS waves)))) (VP (VBZ is) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS waves)) (SBAR (WHNP (WDT that)) (S (VP (VBP go) (PP (IN past) (NP (NP (DT a) (VBN fixed) (NN point)) (PP (IN in) (NP (NP (DT a) (NN period)) (PP (IN of) (NP (NN time)))))))))))))))) (. .)))
that the frequency of waves is the number of waves that go past a fixed point in a period of time.
(ROOT (S (NP (NP (DT The) (NN frequency)) (PP (IN of) (NP (DT a) (NN wave)))) (VP (VBZ is) (NP (NP (DT the) (NN reciprocal)) (PP (IN of) (NP (NP (DT the) (NN period)) (PP (IN of) (NP (DT the) (NN wave))))))) (. .)))