Stability

Stability refers to the ability of an object to return to its original position after it has been tilted slightly.

Three types of equilibrium

Stable Equilibrium

If the object returns to its original position without toppling after being displaced slightly, it is said to be in stable equilibrium.

Criteria
Position of CG	Not applicable	CG is raised.
Relationship between line of action of weight and base of block	the line of action of weight W lies within the base area of block.	the line of action of weight W still lies within the base area of block.
Moment about pivot	No moment	Anticlockwise moment produced by weight about pivot causes the block to return to its original position.

If it continues to move away from its original position after being displaced, it is said to be in unstable equilibrium.

Criteria
Position of CG	Not applicable	CG is lowered.
Relationship between line of action of weight and base of block	the line of action of weight W lies within the base area of the block.	the line of action of weight W lies outside the base area of the block.
Moment about pivot	No moment	Clockwise moment produced by weight about pivot causes the block to topple.

If it stays in its new position after being displaced, it is said to be in neutral equilibrium.

Criteria
Position of CG	CG remains at the same level. Neither rise nor fall.
Moment about point of contact	No moment is provided by the weight about the point of contact to turn the block.

To increase the stability of an object, we should ensure that: