What is defined as the reluctance of an object to change its current state of motion?

Inertia is the concept that describes an object’s resistance to changes in its state of motion. When an object is at rest, inertia keeps it at rest, and when it is in motion, inertia keeps it moving in the same direction at the same speed unless acted upon by an external force. This principle is rooted in Newton's First Law of Motion, which states that an object will not change its velocity unless a net force is applied.

Equilibrium refers to a state where the forces acting on an object are balanced, resulting in a stable condition without any change in motion. Acceleration is the rate of change of velocity of an object and involves both speed and direction, but does not inherently describe the reluctance to change motion. Momentum pertains to the quantity of motion an object has, calculated as the product of its mass and velocity, but again does not specifically address reluctance to change its state. Thus, inertia is the most accurate term to represent the reluctance of an object to alter its current state of motion.