In the context of Newton’s Second Law, mass is a measure of the inertia of an object; that is, it is a measure of how that particular object resists a change in motion due to a force (we can think of ...In the context of Newton’s Second Law, mass is a measure of the inertia of an object; that is, it is a measure of how that particular object resists a change in motion due to a force (we can think of a large acceleration as a large change in motion, as the velocity vector of the object will change more). There is no reason that the mass that is used to calculate weight, \(F_g=mg\), has to be the same quantity as the mass that is used to calculate inertia \(F=ma\).
