A man hauls a sledge with mass $25\,\text{kg}$ over level ground using a horizontal force of $60\,\text{N}$. A frictional force of $20\,\text{N}$ acts constantly on the sledge. What is the acceleration of the sledge?
- A$0.63\,\text{m s}^{-2}$
- B$1.6\,\text{m s}^{-2}$
- C$2.4\,\text{m s}^{-2}$
- D$3.2\,\text{m s}^{-2}$