A uniform plank is supported on a pivot at its mid-point. Two weights are placed on the plank, with one weight on each side of the pivot in the positions shown. A vertical force is then applied at point X so that the plank is in equilibrium. What are the magnitude and direction of this force?
- A$2.0\,\text{N}$ downwards
- B$2.0\,\text{N}$ upwards
- C$4.0\,\text{N}$ downwards
- D$4.0\,\text{N}$ upwards