Giant Lever

An object behaves as though its entire weight is concentrated at a single point. This point is called its center of gravity. The center of gravity of an object is not necessarily at the geometric center of the object, nor, for that matter, does it have to be located within the object at all. An object will move until its center of gravity is located at the lowest possible point. This is why humans must balance to stand upright. If we did not balance our center of gravity over our feet, we would tip over.