What this calculator does
Acceleration & stopping distance works out uniform acceleration, braking distance and reaction gap. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulaa = (v−u)/t; s = ut + ½at²; stopping distance = v·t_reaction + v²/(2μg)
The inputs explained
| Field | What to enter |
|---|---|
| Initial speed (km/h) | A number, measured in km/h. Starts at 0. |
| Final speed (km/h) | A number, measured in km/h. Starts at 100. |
| Time taken (s) | A number, measured in s. Starts at 8. |
| Braking friction coefficient | A number. Starts at 0.7. |
| Reaction time (s) | A number, measured in s. Starts at 1.5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with initial speed
Every other input is held at the calculator’s starting values while initial speed varies. Select any row to load that scenario into the calculator.