Question: I'm currently working on a problem in which an object's speed remains the same, but it experiences a change in direction after some time. I'm fairly sure it experiences an acceleration in order to change direction.

However, I am confused because of the change in direction. 

I want to use the formula $A\_x = \Delta v / \Delta t $. Since the object experiences a change in direction at some point but still travels at the same speed, would the second velocity technically be negative? Like so:

$V\_1$ = 5.0m/s
,$V\_2$ = 5.0m/s,
$T\_1$ = 0 seconds, $T\_2$ = 10 seconds

$A\_x = V\_1 - (-V\_2) / T\_1 - T\_2 $

Also, does it matter which direction? Would it be the same as travelling right and then turning left/right/around?

Answer: 
> 
> I'm fairly sure it experiences an acceleration in order to change direction.
> 
> 
> 

Yes, any change in velocity means an acceleration has occurred. That includes a change in direction of the velocity.

> 
> Since the object experiences a change in direction at some point but still travels at the same speed, would the second velocity technically be negative?
> 
> 
> 

If the first velocity is in the positive direction, yes the second might be negative. Is this a 1-dimensional problem?

> 
> I want to use the formula $A\_x=\Delta v/ \Delta t.$
> 
> 
> 

That will give you the **average** acceleration over the total time. It tells you nothing about the instantaneous acceleration at any specific time. Also, for $A\_x$ you would use $\Delta v\_x$.

Any curvilinear motion (which can't happen in 1-D motion) requires a sideways acceleration component of $$ a\_{\perp} = \frac{v^2}{r} $$ where $v$ is the instantaneous speed and $r$ is the instantaneous radius of curvature.
That is wrong.
In uniform circular motion you have to use this equation:
$$a=v^2/r $$
where $a$ is the acceleration and 
$v$ is the speed and $r$ is radius of the circular path.
You have to know the radius of the circular path because an object with speed 5m/s will have different acceleration in circular paths with different radius.
In short ,yes direction matter.