A box with mass $8.0\,\text{kg}$ is at rest on a horizontal rough surface. A string attached to the box runs over a smooth pulley and carries a $2.0\,\text{kg}$ mass at the other end. Once the box is released, a frictional force of $6.0\,\text{N}$ acts on it. What is the acceleration of the box?
- A$1.4\,\text{m s}^{-2}$
- B$1.7\,\text{m s}^{-2}$
- C$2.0\,\text{m s}^{-2}$
- D$2.6\,\text{m s}^{-2}$