( ( Mass ( on ( ( a ( Vertical Spring ) ) ( When ( ( ( simple harmonic ) motion ) ( is ( ( ( discussed ( in ( introductory textbooks ) ) ) , ) ( ( the mass ) ( connected ( to ( the spring ) ) ) ) ) ) ) ) ) ) ) ( usually ( ( slides ( on ( a ( frictionless ( horizontal surface ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (NNP Mass)) (PP (IN on) (NP (NP (DT a) (NNP Vertical) (NNP Spring)) (SBAR (WHADVP (WRB When)) (S (NP (ADJP (JJ simple) (JJ harmonic)) (NN motion)) (VP (VBZ is) (VP (VP (VBN discussed) (PP (IN in) (NP (JJ introductory) (NNS textbooks)))) (, ,) (NP (NP (DT the) (NN mass)) (VP (VBN connected) (PP (TO to) (NP (DT the) (NN spring)))))))))))) (ADVP (RB usually)) (VP (VBZ slides) (PP (IN on) (NP (DT a) (JJ frictionless) (JJ horizontal) (NN surface)))) (. .)))
Mass on a Vertical Spring When simple harmonic motion is discussed in introductory textbooks, the mass connected to the spring usually slides on a frictionless horizontal surface.
(ROOT (S (NP (NP (DT An) (NN object)) (VP (VBN attached) (PP (TO to) (NP (NP (DT a) (NN spring)) (VP (VBG sliding) (PP (IN on) (NP (DT a) (JJ frictionless) (NN surface)))))))) (VP (VBZ is) (NP (NP (DT an) (JJ uncomplicated) (NN type)) (PP (IN of) (NP (ADJP (JJ simple) (JJ harmonic)) (NN oscillator))))) (. .)))
An object attached to a spring sliding on a frictionless surface is an uncomplicated type of simple harmonic oscillator.