centrifugal vs centripetal

centrifugal

noun
  • A rotating machine used to separate massecuite into sugar crystals and molasses. 

adj
  • Tending, or causing, to recede from the center. 

  • Expanding first at the summit, and later at the base, as a flower cluster. 

  • Having the radicle turned toward the sides of the fruit, as some embryos. 

centripetal

adj
  • Directed towards the central nervous system; afferent. 

  • Directed or moving towards a centre. 

  • Of, relating to, or operated by centripetal force. 

How often have the words centrifugal and centripetal occurred in a corpus of books? (source: Google Ngram Viewer )