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Stability is a measure of how likely it is for an object to topple over when pushed or moved.

Stable objects are very difficult to topple over, while unstable objects topple over very easily.

Objects with a wide base, and a low centre of gravity, are more stable than those with a narrow base and a high centre of gravity.

The yellow car has a wider wheel base and lower centre of gravity than the blue car.

It is more stable.

The wheel acts as the pivot for the car.

The weight has a turning effect or moment, which causes the car to topple over or fall back.

A double decker bus is stable as it has a:

• low centre of gravity because of its low, heavy engine and heavy bottom deck;
• wide wheel base.

A traffic cone is stable as it has a:

• low centre of gravity G because of its heavy base;
• wide base.