placate vs work up

placate

verb
  • To calm; to bring peace to; to influence someone who was furious to the point that they become content or at least no longer irate. 

work up

verb
  • To raise; to excite; to stir up. 

  • To give (a patient) a general medical examination to assess health and fitness. 

  • To develop. 

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