Fig 14 shows a free-standing display board used at a trade show. The display board is tall and narrow, measuring 2 metres high and 0.8 metres wide. It rests...

(a) The centre of gravity is the point through which the entire weight of an object appears to act, or the single point at which the object would balance perfectly. [1]

Every particle in an object is pulled downward by gravity. The centre of gravity is the point where all these individual gravitational forces can be considered to act as a single resultant force. For a uniform, symmetrical object, the centre of gravity is at its geometric centre. For irregular or non-uniform objects, the centre of gravity shifts toward the heavier parts.

(b) Two ways to improve the stability of the display board: [2]

1. Widen the base of the display board to increase the area of support. A wider base means the vertical line through the centre of gravity is more likely to remain within the footprint of the base when the board is tilted by a small force. The board must be tilted through a greater angle before it topples, making it more stable.
2. Lower the centre of gravity by moving the heavy brochure holders to a lower position on the board, or by adding weight (such as sandbags or a heavy plinth) at the base. A lower centre of gravity means the board must be tilted further before the line of action of its weight passes beyond the edge of the base. This increases the restoring moment that returns the board to its upright position.