Try balancing a cork on the tip of a nail. It is very difficult indeed if not impossible. The centre of gravity is high above the point of rotation and gravity will act to push the cork over.

However, if you connect two forks as shown on the right, the cork becomes extremely stable and can balance on the tip of the nail with ease. The centre of gravity has shifted to a point below the point of rotation. This makes the structure very stable. Note that the centre of gravity does not appear on the structure itself but is found in a space between the two forks.