hitting vs knocking

hitting

noun
  • A series of hits or blows directed at a person or object. 

  • The batter's hitting improved with practice. 

knocking

noun
  • An act in which something is knocked on, or the sound thus produced 

  • A repetitive ping, knock, or similar sound coming from an engine in which there are repeated uncontrolled explosions in the combustion chamber. 

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