( ( A block ) ( ( slides ( on ( ( a ( frictionless surface ) ) ( in ( ( simple harmonic ) motion ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN block)) (VP (VBZ slides) (PP (IN on) (NP (NP (DT a) (JJ frictionless) (NN surface)) (PP (IN in) (NP (ADJP (JJ simple) (JJ harmonic)) (NN motion)))))) (. .)))
A block slides on a frictionless surface in simple harmonic motion.
(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.