Theory:

Objective:
  
In this exercise we learn about stability and it's various types.
 
Stability:
The stability is a measurement of the object’s ability to maintain its original position.
 
If the object can maintain it's original position of all the circumstances then the object said to be more stable.
There are three types of stability.
 
1. Stable equilibrium
  
2. Unstable equilibrium
  
3. Neutral equilibrium
  
Stable equilibrium:
The objects are said to be stable when the it is tilted, the vertical line through its centre of gravity still falls within its base.
 
Due to the large base of an object the vertical line through the centre of gravity falls within it's base
 
Therefore the large base of an object gives more stable to the objects.
Example:
bottle.JPG
 
See the above figure, when we slightly tilt the bottle shaped objects without toppling. And we can see that the centre of gravity is raised when it is displaced.
 
Observe that the vertical line through its centre of gravity still falls within its base.
 
So the object can return to its original position. Because this object have large base.
 
Therefore, the objects which have a large base are more stable.
Unstable equilibrium:
The object will be unstable when the it is tilted, the vertical line through its centre of gravity does not falls within its base.
 
Due to the small base of an object the vertical line through the centre of gravity does not falls within it's base. 
 
Therefore the small base of an object gives less stable to the objects.
 
bottle2.JPG
 
Neutral equilibrium:
Now we see the condition of an object when it's in the neutral state.
  •  The neutral equilibrium causes the object to topple.
  • The object's centre of gravity remains at the same height when it is displaced.
The below figure explains the object condition at the neutral equilibrium.
 
nuetral.JPG
 
We have discussed about the stability and types of stability, now we learn at what are the certain conditions that can increase the stability of an object.
The conditions for stability:
  • Increase the area of its base
  • Centre of gravity should be lower.
Because a heavy base lowers at the centre of gravity So the box does not tip over.
Reference:
Tamil Nadu text book 7th std science: https://drive.google.com/file/d/1-_TOLPPHJVDUKb67V5dqzy8vW422bgGk/view