What is the difference between velocity and speed?
Velocity is a vector (displacement/time); speed is a scalar (distance/time). A car going in a circle at constant speed has changing velocity (direction changes).
Velocity / Speed Calculator
v = Δx / Δt
Calculate average velocity or speed from displacement and time. v = Δx/Δt.
Calculate
Enter values above to calculate
How it calculates
1
v = Δx / Δt
2
Δx in metres, Δt in seconds
3
Result in m/s
Formula
v = Δx / Δt
Variable Table
| Symbol | Quantity | SI Unit |
|---|---|---|
| v | Velocity | m/s |
| Δx | Displacement | m |
| Δt | Time interval | s |
How to Use This Calculator
This velocity / speed calculator is built for quick physics checks and worked-problem review. Enter values in the units shown beside each input, then compare the result with the formula and variable table before using it in a longer solution. The calculator does the arithmetic, but the physics still depends on choosing a model that matches the situation.
Start by identifying the system, the known quantities, and the quantity you want to find. If a value is given in a non-SI unit, convert it before substitution. A correct numerical answer with mixed units can still be physically wrong, especially when squared units, inverse seconds, charges, temperatures, or distances are involved.
Assumptions and Limits
The formula v = Δx / Δt is a model, not a universal description of every possible case. It assumes the quantities in the variable table are the relevant quantities for the problem and that hidden effects are either negligible or already included in the inputs. If friction, drag, relativistic speeds, changing fields, non-constant temperature, or geometry-specific effects matter, check whether a more complete model is needed.
Use the result as a magnitude and units check. Ask whether the answer has the right sign, whether it grows or shrinks when an input changes, and whether the limiting cases make sense. Setting an input to zero, doubling a quantity, or using a very large value is often enough to catch a formula choice or unit mistake before it reaches a final answer.
Worked Example
An object moves 100 m in 10 s. Find average speed.
Step 1: v = Δx / Δt
Step 2: v = 100 / 10
Answer: v = 10 m/s
Common Mistakes
- Velocity is displacement/time (vector); speed is distance/time (scalar). They differ if path is curved
- Average velocity ≠ instantaneous velocity unless motion is uniform
- Convert km/h to m/s: multiply by 1000/3600 = 5/18 ≈ 0.2778
Related
Frequently Asked Questions
How do I convert m/s to km/h?
Multiply by 3.6. So 10 m/s = 36 km/h.