Calculating Distance for Negative Acceleration

[CarlosMarti12]

Homework Statement

Suppose an object has a velocity $v$ and an acceleration of $a$, where $a$ is negative. The object will eventually reach a velocity of zero $v = 0$. How much distance will the object travel until $v = 0$?

Homework Equations

v = u + at
s = 0.5(u+v)t
s = ut + 0.5 at²
v² - u² = 2as

The Attempt at a Solution

Since v² - u² = 2as, s = -u²/2a. I implemented this formula into a program I am using, but the object did not stop at the given distance. Am I doing something obviously wrong here? Any help would be greatly appreciated.

 

[dipole]

Well, using equation 1, set v = 0 and solve for t. Then plug that value into equation 3.