Final answer:
In linear kinetics, mass is equivalent to inertia; it is the measure of an object's resistance to changes in motion. In rotational dynamics, the moment of inertia is the rotational equivalent, determining the torque required for angular acceleration.
Step-by-step explanation:
The concept equivalent to inertia in linear kinetics is mass. Inertia is the property of an object that resists changes to its state of motion, and mass quantifies this property in linear motion. In rotational dynamics, the analogous concept to inertia is the moment of inertia, often represented as I or mr², where m is the mass and r is the distance from the axis of rotation. The moment of inertia determines how much torque is needed to achieve a certain angular acceleration, similar to how mass determines how much force is needed to achieve a certain linear acceleration.
The moment of inertia plays a critical role in rotational dynamics, particularly in equations that describe rotational motion, like the general relationship among torque, moment of inertia, and angular acceleration (net t = Iα), which is the rotational analog of Newton's second law of motion (F = ma).