The acceleration of the truck is -6.8 m/s².
Given data:
The inital speed is u=17 m/s.
The time taken is t=2.5 s.
The truck come to a compelet stop that means the final speed of truck is zero, i.e., v=0 m/s.
The formula for the acceleration is given by,
![\begin{gathered} a=(v-u)/(t) \\ a=\frac{0\text{ m/s-17 m/s}}{2.5\text{ s}} \\ a=-6.8\text{ m/s}^2 \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/umh1yxrwttlyommmerfbjofkkfyicv4dju.png)
Thus, the acceleration of the truck is -6.8 m/s².