Recall that an object's average velocity includes a value (also called magnitude) and a direction.

Question

Recall that an object's average velocity includes a value (also called magnitude) and a direction.

This means that speed and velocity can never be the same because speed doesn't include direction. However, it is possible for the speed to be equal to the magnitude of the average velocity. Under what circumstance will an object's average speed have the same value as the magnitude of its average velocity?

Answer 1

An object's average speed will have the same value as the magnitude of its average velocity when the object is moving in a straight line and the direction of motion is constant over the entire duration of the motion. In this case, the average speed is calculated by dividing the total distance traveled by the total time taken, while the magnitude of the average velocity is calculated by dividing the total displacement (change in position) by the total time taken. Since the object is moving in a straight line, the total distance traveled is equal to the total displacement. Therefore, the average speed and magnitude of average velocity will be the same.