Appreciating the Importance of Stability


1. Stability is very important. The use of unstable objects would lead to accidents. There will be great losses of property and lives if the objects around us were to topple over easily.


2. In fact, factors of stability are also found in nature. For example, animals like crocodiles, lizards and tortoises are very stable due to their low centre of gravity and large supporting base. A giraffe spreads its legs wide apart to increase its base area and to lower its centre of gravity when drinking water.


Improving The Stability Of Objects

1. Two ways to make an object more stable:

    (a) Lowering its centre of gravity
         This can be done either by reducing its height or attaching a heavy weight onto its

    (b) Increasing its base area


2. Figure 9.16 shows a few examples how to improve the stability of an object.



Applying The Principle Of Stability

1. The principle of stability is widely used in designing buildings, vehicles, furniture and appliances. They are designed to have a low centre of gravity and a large base area for stability purposes.


2. Here are some examples:

    (a) Tall buildings, houses, schools and factories are usually built on a heavy concrete
         foundation for stability. This lowers the centre of gravity of the buildings.


    (b) A racing car is built low so that it has a low centre of gravity. Its tyres are wide and
          set wide apart to give the car a large base area.

    (c) Lorries, trucks, buses and double-decker buses are designed with their heavy engines
         as near to the ground as possible to lower their centres of gravity.

    (d) Furniture such as cupboards, tables and chairs are made more stable by having broad
         legs or legs that are set wide apart.

    (e) The bottom of a glass is thicker and heavier to lower its centre of gravity.

    (f) Many electrical appliances such as table lamps, standing fans and refrigerators, and
         laboratory apparatus such as retort stands and Bunsen burners are designed with a
         large and heavy base.

    (g) Laboratory apparatus such as tripod stands, conical flasks and measuring cylinders
         have large base areas.


3. In fact, we also apply the principle of stability in many of our daily activities.

    (a) When arranging items in a tall shelf, we arrange the heavier items at the bottom

    (b) An old person will bend forward and use a walking stick to make himself more stable
         while walking.

    (c) Boxers and people who practice martial arts such as karate always stand with their
         feet wide apart and their body low when fighting.

    (d) The passengers of a double-decker bus are not allowed to stand on the upper deck
          so that the centre of gravity of the bus is not raised.