Question: is kinetic energy a quantitative measure of inertia

Answer: No, By this formula, the greater its mass, the less a body accelerates under a given force. The masses defined by the above formulas are equal because the latter formula is a consequence of the former, if mass does not depend on time and velocity. Thus, ``mass is the quantitative or numerical measure of a body's inertia, that is of its resistance to being accelerated''.