This document discusses stability and center of gravity. It defines an object in equilibrium as stationary or at rest, with all objects having a point of equilibrium. The center of gravity is the point where the earth's gravitational force acts on an object, concentrating its weight, and is the same point as the object's equilibrium. An object's stability depends on the position of its center of gravity - generally, a lower center of gravity makes an object more stable, as seen in examples of vehicles, boats, and animals. The principle of stability through center of gravity should be applied in design.

1. Chapter 9
Stability

2.  An object is said to be in equilibrium when it
is stationary or at a rest.
 All object have a point of equilibrium.
 An object can be balanced at its point of
equilibrium.

4.  Ina regular objects , the point of equilibrium
lies at the intersection of its diagonals.

5.  The point of equilibrium of irregular shape
Point of Equilibrium
The point of intersection of the lines is the
point of equilibrium of the irregular shape

6.  The centre of gravity of an object is the point at which
the earth’s gravity acts on that object.
 The weight of an objects is due to the gravitational
force acting on it.
 The gravitational force acts on all parts of the
object, but the weight can be considered to concentrate
at one point. This point is called the centre of gravity of
the object.
 The point of equilibrium of an object is also the
centre of gravity.
 The centre of gravity and the point of equilibrium
are also defined as the point at which the whole
weight of an object appears to act.

8.  The stability of an object is its ability to
maintain its original position.
 The stability of and object is affected by its
centre of gravity and base area

9.  Generally an object with a low centre of gravity
is more stable than an object with a high centre of
gravity.

10.  A racing car is designed to have a low center of gravity.
 Heavy vehicles such as lorries and buses have heavy
engines. These engines are placed at the bottom to lower their
centre of gravity. This makes them more stable.
 Passengers in a canoe are advised to sit when the canoe is
paddled. This lowers the centre of gravity of the canoe and
provides greater stability.
 A motorcyclist bends his body forward to lower his centre of
gravity so that he becomes more stable while riding his
motorcyles.
 The lower of the glass is made thicker and heavier . This lowers
its center of gravity and makes it more stable.
 The passengers of a double-decker bus are not allowed to stand
on the upper deck. This is to lower the centre of gravity of the
bus and thus give it greater stability.

11. The principle of stability should be applied
when designing the shapes of
buldings , vehicles, furniture, apparatus used in
laboratories and the utensils and tools that are in
daily use.

12. The stability of a person’s body depends on the position of the
centre of gravity

13. The giraffe stands with its legs spread wide apart
to increase its base area and to lower its centre of
gravity. This makes it more stable.