A ball with mass $200\,\text{g}$ is projected horizontally at a speed of $20\,\text{m s}^{-1}$ towards a vertical wall. It remains in contact with the wall for $0.10\,\text{s}$ before bouncing back along the same line with a speed of $10\,\text{m s}^{-1}$. What is the average force exerted by the wall on the ball during the collision?
- A$20\,\text{N}$
- B$60\,\text{N}$
- C$20\,\text{kN}$
- D$60\,\text{kN}$