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Imagine that a real three dimensional object is placed on a smooth flat table. Configurations where the object can exist at rest without moving are called static equilibrium configurations. Some of these static equilibrium configurations are stable: the object will eventually return to the position of equilibrium after a tiny nudge. Some are unstable: the object eventually moves to a new position of equilibrium following a tiny nudge.
Find some solids of essentially uniform density near to you. How many stable and unstable static equilibrium configurations do they have? You could imagine these and then test them out with nudges. Practically speaking many configurations will eventully change with large enough nudges. Perhaps some configurations are more stable than others?