The center-of-gravity of an object is the point that moves as though the weight of the object is concentrated there.

The center-of-gravity of an object, or a collection of objects, can be found using:

Xcog

=

x1m1g +x2m2g + ... m1g + m2g + ...

In a uniform gravitational field, weight and mass are proportional to each other and the center-of-mass and the center-of-gravity are the same point. They're different if the gravitational field is non-uniform.

The center-of-gravity can be determined by hanging an object from a support. In a stable equilibrium position the center-of-gravity will always hang directly below the support.