heaviness vs inertness

heaviness

noun
  • The state of being heavy; weight, weightiness, force of impact or gravity. 

inertness

noun
  • Absence of the power of self-motion; inertia. 

  • Quality of being unreactive with other chemical compounds or elements. 

  • Lack of activity or exertion; habitual indisposition to action or motion 

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