Library / Foundations: Physics / FPH-01
Foundations: Physics
Mean velocity
Average velocity from displacement and time.
- Ref
- FPH-01
- Rev
- v1
- Field
- Foundations: Physics
- Result
- v̄ [m/s]
Mean velocity uses displacement (a straight-line change of position with direction). Mean speed uses the total distance divided by elapsed time.
Average velocity is how far you end up from where you started, divided by how long it took.
Calculator
m/s
m
s
- Speed in km/h28.8 km/h
- Time per 100 m12.5 s
What drives the result
Each variable is moved across its typical range while the others stay at the values above. The longest bar is the key driver.
Mean velocity (m/s) current value 8 m/s
ΔtTime takenKey driver
0.167100
ΔxDisplacement
0.0880
- Multiply m/s by 3.6 to get km/h.
- Mean velocity can be zero for a round trip, while mean speed is not.
Chart data as tables
Ranked variables
| Variable | Typical range | Lowest result | Highest result | Swing (m/s) | Local step | Change in result |
|---|---|---|---|---|---|---|
| Δt Time taken | 1 to 600 s | 0.1667 | 100 | 99.83 | +10% | −9.09 % |
| Δx Displacement | 1 to 1,000 m | 0.08 | 80 | 79.92 | +10% | +10 % |
Sweep of Time taken
| Time taken (s) | Mean velocity (m/s) |
|---|---|
| 1 | 100 |
| 2.225 | 44.95 |
| 4.949 | 20.21 |
| 11.01 | 9.082 |
| 24.49 | 4.082 |
| 54.49 | 1.835 |
| 121.2 | 0.8249 |
| 269.7 | 0.3708 |
| 600 | 0.1667 |
Sweep one variable
Mean velocity (m/s)Hover, touch, or use the arrow keys on the chart
Variables and how each one contributes
v̄
Mean velocity
What the equation gives you. Everything else feeds it.
Δx
Displacement
Change in position. Directly proportional.
Δt
Time taken
Elapsed time. Inversely proportional.
Worked example with the values above
- Displacement 100 m over 12.5 s.
- Divide: 100 / 12.5.
- Mean velocity 8 m/s.
Assumptions and limits
- Straight-line displacement.
- Time measured over the same interval.
Common mistakes
- Using distance travelled instead of displacement for velocity.
- Mixing km/h and m/s.
Statistics and uncertainty
Timing error usually dominates: a stopwatch good to ±0.2 s over 12.5 s gives about 1.6% error in the velocity.
Where it is used
- Vehicle and projectile speeds.
- Time-of-flight range calculations.
Maths you need
- Units: m, s and m/s
- Division: distance over time