When you see a traffic light turn red, you apply the brakes until you come to a stop. if your initial speed was 12 m/s, and you were heading due west, what was your average velocity during breaking? assume constant deceleration.

For rectilinear motion having a constant acceleration, the average velocity is meant literally as an average of the initial and final velocity. Generally, the average velocity is equal to the total distance to the total time. However, for constant acceleration, it is also equivalent to the mean of the two velocities. Hence,

average velocity = (0 + 12 m/s)/2 = 6 m/s

Since the motion is heading west, according to conventionality, the velocity should have a negative sign. So, the average velocity is -6 m/s.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.