Answer:
![10.0 m/s^2](https://img.qammunity.org/2020/formulas/physics/middle-school/akv1rxe7ec85ii0trm7s80kwkw98qz4ouv.png)
Step-by-step explanation:
The acceleration of an object is given by
![a=(v-u)/(t)](https://img.qammunity.org/2020/formulas/physics/middle-school/rbz9i28f98a6dvpx0ghax9pxq7qjfdf5sd.png)
where
v is the final velocity
u is the initial velocity
t is the time interval it takes for the velocity to change from u to v
For the car in this problem,
u = 21.0 m/s
v = 46.0 m/s
t = 2.5 s
Substituting, we find the acceleration
![a=(46.0-21.0)/(2.5)=10.0 m/s^2](https://img.qammunity.org/2020/formulas/physics/middle-school/pf2wip79p9yi7sup8jcu4kr1ugxf7wrfi4.png)