The formula to determine the acceleration of an object moving in a straight line is:

```

a = (v - u) / t

```

where:

- `a` is the acceleration in meters per second squared (m/s²)

- `v` is the final velocity in meters per second (m/s)

- `u` is the initial velocity in meters per second (m/s)

- `t` is the time taken in seconds (s)