Answer:
The average acceleration of train is
![5.34\ m/s^2](https://img.qammunity.org/2021/formulas/mathematics/college/r6dp3qhk858bp4xiyxn0z1y2cc7fsvkkms.png)
Explanation:
We have,
A train that slows down from 15 m/s to 8.6 m/s in 1.2 s. It means that 15 m/s is its initial velocity and 8.6 m/s is its final velocity.
It is required to find the average acceleration of the train.
![a=(v-u)/(t)\\\\a=((8.6-15)\ m/s)/(1.2\ s)\\\\a=-5.34\ m/s^2](https://img.qammunity.org/2021/formulas/mathematics/college/6ums1k0mqgi6t3a0wud9typ7nm1ij33fao.png)
The average acceleration of train is
. Negative signs shows that the train is decelerating.