What term describes the length and direction of an object's change in position from its starting point?

The term that describes the length and direction of an object's change in position from its starting point is displacement. Displacement is a vector quantity, which means it has both magnitude and direction. It takes into account not only how far an object has moved but also in which direction it has moved from its original position.

For example, if an object moves from a starting point A to point B, the displacement would be the straight-line distance from point A to point B, along with the direction of that straight line. This is different from distance, which only measures how much ground is covered regardless of the direction.

Velocity, while related, specifically refers to the rate of change of displacement over time, indicating how fast and in what direction an object is moving. Acceleration refers to the rate of change of velocity, representing how quickly an object's velocity changes over time. These terms are interrelated but describe different concepts regarding motion.