Resistance to a change in motion is primarily due to?

Resistance to a change in motion, or inertia, is fundamentally related to the mass of the object. According to Newton's first law of motion, an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity unless acted upon by an external force. This property of matter is directly tied to its mass.

The greater the mass of an object, the greater the force required to change its state of motion, whether starting it moving, stopping it, or changing its direction. This principle explains why heavier objects are harder to accelerate or decelerate compared to lighter ones. Mass, therefore, is a crucial factor in determining the resistance to changes in motion.

While factors such as acceleration, friction, and speed can influence motion, they do not primarily determine resistance to change; rather, they act as forces or conditions that affect motion under specific circumstances. For example, friction can resist motion, but it is not the inherent property of an object that dictates how much force would be required to change that motion in the first place.