The diagram represents a barrel hanging from a frictionless pulley fixed to a building. The rope that supports the barrel passes over the pulley and is tied 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 top of 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 it from the stake, the man continues to hold the rope and is pulled upwards as the barrel drops. 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$19\,\text{m s}^{-1}$