What is the center of mass?

Centroid-the centroid of an object (or object system) is an important reference point for studying the mechanical motion of an object (or object system). When the force (or resultant force) passes through this point, the object only translates and does not rotate; Otherwise, the object will rotate around this point when moving. When studying the motion of the center of mass, it can be considered that the mass of an object is concentrated in the center of mass. Theoretically, the center of mass is the average center of the mass distribution of an object obtained by the weighted average method.