( ( ( inertia balance ) ( by ( using ( a stroboscope ) ) ) ) . )
(ROOT (NP (NP (NN inertia) (NN balance)) (PP (IN by) (S (VP (VBG using) (NP (DT a) (NN stroboscope))))) (. .)))
inertia balance by using a stroboscope.
(ROOT (S (NP (NNS Centrifuges)) (VP (VBP use) (NP (NN inertia)) (S (VP (TO to) (VP (VB perform) (NP (PRP$ their) (NN task)))))) (. .)))