Stability CHAPTER 9
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Stability
CHAPTER 9
CHAPTER 9
UNIT 9.1 Understanding that the centre of gravity affects stability
Stability
Determine the point of equilibrium in regular and irregular
shapes
Relate the point of equilibrium as the centre of gravity of
objects
Relate the centre of gravity to the stability of objects
Stability of an object refers to its ability to maintain its original
position.
WHAT IS STABILITY?
An object is unstable if it cannot return to its original position when tilted and released.
Tilted
and released
It cannot returns to its original position
An object is stable if it can return to its original position when tilted and released.
Tilted
and released
It returns to its original position
The Point of Equilibrium
What is the ‘point of equilibrium’?
The point of equilibrium is the point where the whole weight of an object appears to act on.
The point of equilibrium of an object is actually the
centre of gravity of an object
It is the point at which the Earth’s gravity acts on an object.
Centre of
gravityCentre of
gravity
Location of the centre of equilibrium
Point Of Equilibrium / Centre of Gravity
•Gravitational force acts on every part of an object.
•However, its weight can be considered to be concentrated at one point. This point is its centre of gravity.
•The object can be balanced when supported at its centre of gravity.
9.1 Stability
The point of equilibrium of an irregular shape can be determine as follow
1. The cardboard was suspended consecutively from the points A, B, and
C together with a plumb line.
2. The 3 verticals lines that were drawn along the plumb line intersected
at a point.
3. The cardboard could be balanced at the point of intersection of the 3
vertical lines.
Thumb tack
Thick cardboard ofirregular shape
Plumb line
The point of equilibrium of an irregular shape can be determine as follow
4. This means,
(a) Point of equilibrium of an irregular
shape is located at the point of
intersection of the 3 lines
(b) Point of equilibrium of an irregular
shape can be determined by this
experiment.
Result :
Step 1: Step 2: Step 3:
Centre of Gravity in Regular Shapes
The centre of gravity of regularly shaped objects is usually at the centre
c.g.
c.g.c.g.
2 factors affecting the stability of an object
• The position of the centre of gravity of the object
• The base area of the object
Centre of gravity
Base area
Centre of gravity of an Object
The lower the centre of gravity of an object, the more stable the object.
StableMore stable
Most stable
Base area of an Object
The larger the base area of an object, the more stable the object.
Stable More stable
Most stable
CHAPTER 9
UNIT 9.2 Appreciating the importance of stability
Stability
Suggest ways to improve the stability of objects around them
Explain with examples the application of stability in life
How To Improve The Stability Of an Object
Improving the stability of an
object
Lowering its centre of gravity
Increasing its base area
Importance of Stability
Many appliances are designed to have a low centre of gravity for stability:
Lower the centre of gravity
The principle of stability is applied to many aspects of our daily life
Increase base area to gain stability
The principle of stability is applied to many aspects of our daily life
Increase base area to gain stability
SMK Perempuan Likas
Sabah
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