Inertial Mass

1. (physics) The mass of an object measured as its resistance to being accelerated by an applied force; it is equal to its gravitational mass.

Synonyms

• passive gravitational mass (in Einsteinian and Newtonian gravitation)

Inertial mass refers to the measure of an object's resistance to changes in its state of motion, specifically its resistance to acceleration when subjected to an external force. In other words, inertial mass quantifies how an object responds to applied forces and their resulting accelerations. According to Newton's second law of motion, the force (F) applied to an object is equal to the product of its mass (m) and acceleration (a), expressed as (\(F = m \cdot a\)). In this context, inertial mass is a fundamental property that characterizes an object's inertia, representing its tendency to maintain its current state of motion.

The principle of equivalence in general relativity suggests that inertial mass is equivalent to gravitational mass, meaning that the resistance an object exhibits to acceleration under force is numerically equal to its response to gravitational forces.