How to Calculate Average Velocity

Average Velocity is defined as the total displacement divided by the total time taken.

Average Velocity (v) = $\frac{\text{Total Displacement (\Delta x)}}{\text{Total Time Taken (\Delta t)}}$

• Displacement is the shortest straight-line distance from the starting point to the ending point (Final Position - Initial Position).
• The SI unit for average velocity is meters per second (m/s).

If (and ONLY if) an object is moving in a straight line with a constant uniform acceleration, the average velocity can be calculated by simply averaging the initial and final velocities:

Average Velocity = $\frac{\text{Initial Velocity (u)} + \text{Final Velocity (v)}}{2}$

Imagine you run one lap around a 400m circular track in 100 seconds.

• Average Speed = Total Distance / Time = 400m / 100s = 4 m/s.
• Average Velocity = Total Displacement / Time. Since you ended up exactly where you started, your displacement is 0. Therefore, Average Velocity = 0 m/s.