Question 2
In activity 1, four points A, B, C and D are marked on a door and the force needed to open it is measured at each. At which of them is the smallest force needed to start the door turning?
The right answer is the one marked above.
At the point furthest from the hinges. The perpendicular distance from the axis is largest there, so the smallest force is enough to produce the same moment.
It is tempting to pair "smallest force" with "smallest distance". The two change in opposite directions — as the distance grows, the force falls.