If you have the initial velocity (v_i), final velocity (v_f), and acceleration (a), you can use the following equation to calculate the time (t):
v_f = v_i + a * t
Rearranging the equation to solve for time:
t = (v_f - v_i) / a
In this equation, subtract the initial velocity (v_i) from the final velocity (v_f) and divide the result by the acceleration (a). This will give you the time it takes for the object to change velocity from the initial to the final value under the given acceleration.