Answer:
13 m/s
Step-by-step explanation:
The computation of the final velocity is shown below;
We know that 
v^2 = u^2 + 2as
Here v represent the final velocity
u denotes the initial velocity
a denotes the acceleration
And, s denotes the displacement
So, the final velocity is 
 v^2 = (5)^2 + 2(8)(9) 
 = sqrt(25 + 144)
= sqrt(169)
= 13 m/s