Which term refers to resistance against changes in velocity?

The term that refers to resistance against changes in velocity is inertia. Inertia is a property of matter that describes an object's tendency to maintain its state of motion, whether it is at rest or moving at a constant speed in a straight line. According to Newton's first law of motion, an object will remain at rest or in uniform motion unless acted upon by an external force. This means that an object with greater mass has more inertia and requires a larger force to change its state of motion.

Acceleration refers specifically to the rate at which an object's velocity changes over time, which is the opposite of inertia. Friction is a force that opposes the motion of surfaces sliding against one another but is not directly related to the concept of resisting changes in velocity itself. Velocity describes the speed of an object in a specific direction, rather than a property related to resistance. Therefore, inertia is the correct term as it encapsulates the concept of an object's resistance to changes in its motion.