Inertia is defined as?

Inertia is defined as the resistance to a change in motion, which reflects an object's tendency to remain at rest or in uniform motion unless acted upon by an external force. This concept is rooted in Newton's first law of motion, often referred to as the law of inertia.

When an object is at rest, it will stay at rest; when it is moving, it will continue to move at a constant velocity in a straight line. This means that inertia is not about how quickly an object moves (which would relate to its speed) or the force applied to it, but rather about its inherent property that opposes any change to its state of motion.

For example, a heavy object has greater inertia than a lighter one, meaning it requires more force to change its motion. This fundamental understanding is crucial in both physics and exercise science, as it influences movement strategies and the application of force during physical activity.