The diagram depicts a barrel hanging from a frictionless pulley fitted to a building. The rope that supports the barrel passes over the pulley and is fastened to a stake at the foot of the building. A man is standing near the stake. The underside of the barrel is $18\,\text{m}$ above the man’s head. The mass of the barrel is $120\,\text{kg}$ and the mass of the man is $80\,\text{kg}$. After untying the rope from the stake, the man holds onto it and is pulled upwards as the barrel descends. What is the man’s upward speed when his head is level with the bottom of the barrel? (Use $g = 10\,\text{m s}^{-2}$.)
- A$6\,\text{m s}^{-1}$
- B$8\,\text{m s}^{-1}$
- C$13\,\text{m s}^{-1}$
- D$19\,\text{m s}^{-1}$