The document discusses the concept of equilibrium in structures using a seesaw as an example. It explains that a structure is in equilibrium when upward and downward forces are balanced. It then shows a diagram of a seesaw with equal weights on both sides, demonstrating equilibrium as the seesaw stays level. It further explains that adding more weight to one side causes the seesaw to tip in that direction, and equilibrium can be restored by adding equal extra weight to the opposite side to balance the moments.
