Several terms describe an object in motion: speed, velocity, average velocity, direction, distance, displacement and acceleration. Each term represents a different facet of an object's motion. Understanding the difference between velocity and average velocity requires knowledge of all of the principles of motion and the relationship between an object's velocity, speed and average velocity.
Velocity is defined as the rate at which an object changes its position, according to the Physics Classroom. Velocity is speed with a direction; speed is simply how fast an object is traveling. Velocity involves displacement -- how far from its point of origin an object moves. This differs from distance, which only measures how far an object travels and may or may not equal displacement. For displacement and distance to be equal, travel must be in a straight line; changing directions increases distance but may lessen displacement.
Average velocity is displacement divided by the time traveled to achieve an average. Average velocity explains how far an object has traveled from its point of origin and at what rate of speed. When distance and displacement are equal, average velocity and average speed are the same figure. When an object travels in more than one direction, average velocity is less than average speed.
Walk around a typical city block and return to the place you started; you covered distance and produced an average speed, but as far as velocity is concerned, you have not gone anywhere. Your velocity in this case equals zero, as does your average velocity. Now walk one block straight ahead, one block to the left, then one block straight ahead and keep alternating directions. In this example, displacement will be less than distance; velocity will show how far you ended up from your point of origin. End up four blocks from your starting point after an hour, and your average velocity is four blocks per hour -- regardless of distance traveled.
Acceleration describes whether an object is speeding up or slowing down. When determining average velocity over a straight line, acceleration is assumed to be constant, as the displacement occurs at a constant rate over a set period of time.
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