Step-by-step explanation:
It is given that,
Mass of the ball, m = 52 g = 0.052 kg
Initial speed of the ball, u = 28.5 m/s
Final speed of the ball, v = -15.5 m/s (it rebounds)
If the ball is in contact with the wall for 3.45 ms, t = 0.00345 s
Acceleration,
![a=(v-u)/(t)](https://img.qammunity.org/2020/formulas/physics/high-school/ge7n7qpiqku41bi8upy0o4u7eeuffs8qzm.png)
![a=(-15.5-28.5)/(0.00345)](https://img.qammunity.org/2020/formulas/physics/high-school/t97yextow66nxmdi4penhcbihhqx4sw0l2.png)
![a=-12753.62\ m/s^2](https://img.qammunity.org/2020/formulas/physics/high-school/rrj49oz7a4bpuu24h09503s5g2jftavjoy.png)
So, the average acceleration of the ball during this time interval is
. Hence, this is the required solution.