difficulty vs inertness

difficulty

noun
  • Physical danger from the environment, especially with risk of drowning 

  • An obstacle that hinders achievement of a goal. 

  • The state of being difficult, or hard to do. 

  • An objection. 

  • An awkward situation or quarrel. 

  • That which cannot be easily understood or believed. 

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 difficulty and inertness occurred in a corpus of books? (source: Google Ngram Viewer )