How to Calculate Acceleration from a Change in Speed

Calculates acceleration as (final speed − initial speed) ÷ time. Speeds are in m/s, time in seconds, and acceleration in m/s². Slowing down gives a negative value.

Explanation

Acceleration is how much the speed changes each second. Give the starting speed, the final speed and the time taken, and it follows.

a = \dfrac{v - v_0}{t}

$a$ is the acceleration, in m/s²
$v_0$ is the initial speed and $v$ the final speed, both in m/s
$t$ is the time taken, in seconds (s)

The calculator reports the change in speed, $v - v_0$ , alongside the acceleration.

Example

The defaults are an initial speed of 10 m/s, a final speed of 30 m/s and a time of 4 s.

a = \dfrac{30 - 10}{4} = 5\,\mathrm{m/s^2}

The acceleration is 5 m/s² and the change in speed is 20 m/s. In other words, the object gained 5 m/s of speed every second.

Notes

This is the average acceleration across those 4 seconds. If the object sped up unevenly, the average will not reveal it.

Slowing down gives a negative acceleration. Dropping from 30 m/s to 10 m/s in 4 s comes out as −5 m/s². A negative answer is not a mistake.

The time must be greater than zero. Zero or a negative value gives an error.

Speeds go in m/s. Divide km/h by 3.6 to convert: 72 km/h is 20 m/s.