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=\frac{0.05kg[10-(-10)]m/s}{2s}\\\\F=\frac{0.05kg(20m/s)}{2s}\\\\F=0.5kgm/s^2=0.5N](https://tex.z-dn.net/?f=F%3D%5Cfrac%7B0.05kg%5B10-%28-10%29%5Dm%2Fs%7D%7B2s%7D%5C%5C%5C%5CF%3D%5Cfrac%7B0.05kg%2820m%2Fs%29%7D%7B2s%7D%5C%5C%5C%5CF%3D0.5kgm%2Fs%5E2%3D0.5N)
Hence, the average force on the wall will be equal to 0.5N.