When our body is in the standing position it is in a state of unsteady equilibrium because the base is small and the centre of gravity is a long way above it. That is why it has to be balanced by keeping the centre of gravity over the base, otherwise the body would fall over.

Equilibrium: The steadiness of the body depends on the size of its base and the distance of the centre of gravity from that base. An object having a large base and a low centre of gravity is not easily upset.

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