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Average velocity
Beginner
Total displacement divided by total time.
v̄ = Δx/ΔtAverage velocity is total displacement divided by total time. It ignores what happens in between, so it can be zero for a round trip. For constant acceleration it equals (u + v)/2.
Travelling 100 m east in 20 s gives 5 m/s east. A trip east and back in the same 40 s gives 0.
Average velocity is not the average of speeds unless time intervals are equal.
In more detail
Average velocity is the total displacement divided by the total time taken. It can be very different from average speed if the object doubles back.
Real-world uses
- A runner who returns to the start has an average velocity of zero, even though they ran a full distance.
- Transport planners use average velocity between two points to estimate journey times.
- Average speed on a motorway trip is the total distance divided by the total time, including stops, not the average of the speeds.
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Frequently asked questions
How is average velocity different from average speed?
Average speed is total distance divided by time. Average velocity is total displacement divided by time.
Can average velocity be zero?
Yes, if the displacement over the interval is zero, as for a round trip.
Is average velocity the same as the average of the velocities?
Only for constant acceleration over equal time intervals. In general, average velocity is displacement divided by time.
Related topics in Kinematics
Reference frames · Distance vs displacement · Speed vs velocity · Instantaneous velocity · Acceleration · Uniform motion