Instantaneous Velocity Calculator
Work out instantaneous velocity instantly with clear inputs, formula shown and shareable results.
About Instantaneous Velocity Calculator
Under constant acceleration the velocity at any instant is v = u + at, the first of the SUVAT relations. Starting at 5 m/s and accelerating at 2.5 m/s2 for 4 s reaches 15 m/s. The displacement is shown alongside because velocity alone does not say how far the body has moved.
Formulas
Velocity at time t
v = u + a x t
Displacement
s = ut + 0.5 a t^2
Worked example
With the default values below, Instantaneous Velocity Calculator returns Velocity At That Instant of 15.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Initial velocity u
- 5 m/s
- Acceleration a
- 2.5 m/s2
- Time elapsed tminimum 0 s
- 4 s
Results
- Velocity At That Instant
- 15.0000 m/s
- Change In Velocity
- 10.0000 m/s
- Displacement Up To That Time
- 40.0000 m
- Speed In km/h
- 54.000
Step by step
- 1Values used
- 2Velocity at time t
- 3Displacement
- 4Velocity At That Instant= 15.0000 m/s
- 5Change In Velocity= 10.0000 m/s
- 6Displacement Up To That Time= 40.0000 m
- 7Speed In km/h= 54.000
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Does this work with varying acceleration?
No. It assumes acceleration is constant over the interval; otherwise you need the integral of acceleration or a numerical method.
Why can velocity be negative?
Because it is a vector along the chosen axis. A negative result means the body is moving opposite to the direction you called positive.