What does acceleration measure in motion?

Acceleration is defined as the rate of change of velocity with respect to time. It quantifies how quickly an object changes its speed or direction, which is crucial in understanding motion. When an object accelerates, it either speeds up, slows down, or changes direction. This means that acceleration not only involves changes in how fast the object is moving but also any changes in its course, reflecting a comprehensive measure of motion dynamics.

Understanding acceleration as a change in velocity makes it clear that it's specifically concerned with alterations in an object's speed and direction per unit of time, making it distinct from other concepts related to motion. For example, constant speed refers to uniform motion without any change in velocity, and therefore does not account for acceleration in any form. Similarly, concepts like distance and displacement relate to the position of an object rather than the changes in its velocity over time. Thus, the choice that states acceleration measures change in velocity over time accurately encompasses what acceleration represents in the context of motion.