Answer" The average force on the wall be equal to 0.5 N.
Explanation:
To calculate the average force on the wall, we use the following equation:

where,
F = average force = ?N
m = mass of the ball = 0.05kg
= Initial velocity of the ball = -10m/s (negative sign because the ball rebounds)
= Final velocity of the ball = 10m/s
t = time taken by the ball = 2s
Putting values in above equation, we get:
![F=(0.05kg[10-(-10)]m/s)/(2s)\\\\F=(0.05kg(20m/s))/(2s)\\\\F=0.5kgm/s^2=0.5N](https://img.qammunity.org/2018/formulas/physics/high-school/fznpqnlnuyghormetr644aifbmgj1lgsl0.png)
Hence, the average force on the wall will be equal to 0.5N.