View more lessons like this at http://www.MathTutorDVD.com In this lesson, we explain the difference between average speed and average velocity in physics. We start by showing that the average velocity is defined to be the displacement of an object divided by the elapsed time during the motion. Because of this definition, velocity is a vector quantity because the displacement is a vector as well. The speed formula is the exact same equation as the velocity formula with the difference that we take the absolute value of the displacement before doing the calculation. Because of this, speed is defined as distance divided by time elapsed. Speed is not a vector - it is a scalar quantity.