Answer:
![-3m {s}^(-2)](https://img.qammunity.org/2020/formulas/physics/high-school/7sncifs5p5kjdk5xycpjba8c502xwli76v.png)
Step-by-step explanation:
The initial velocity, u, of the car=15m/s
The final velocity, v, of the car =0m/s
Time, t, taken for the car to come to a stop=5s
Acceleration is calculated by,
![a= (v - u)/(t)](https://img.qammunity.org/2020/formulas/physics/high-school/50xdgk1mb5b21e850cu16lrhqvnean005b.png)
By substitution,
![a= (0- 15)/(5)](https://img.qammunity.org/2020/formulas/physics/high-school/ii71drjx8tzpq0z85fxyyd93ddvw6cfh42.png)
![a= (- 15)/(5)](https://img.qammunity.org/2020/formulas/physics/high-school/l9kpqz6o26rhg5zv84v3g0y81t0prbz1va.png)
![a = -3 {ms}^( - 2)](https://img.qammunity.org/2020/formulas/physics/high-school/o7mcau3rfnvlrm2xyhfbd6c5vzfq3clh6m.png)
The negative sign implies that the car has decelerated.