Center of gravity (CoG) is the point in which the weight of an object is balanced. For example, if a seesaw is empty, the CoG is in the middle of the seesaw. If people with different weights occupy the seesaw, the CoG is closer to the heavier person. Likewise, a wheelchair has its own unique CoG. When a person occupies a chair, the CoG changes. A wheelchair has a CoG low to the ground, but when the chair is occupied, the CoG shifts higher.