Neeraj Kumar Singh: Your Academic Support System

Answer

centre of mass is the point where the entire mass of the body acts. It means if have to see any effect regarding mass of body u have to find centre of mass. This point helps in solving problem of mass because mass is distributed throughout mass so its calculation become complex. So this point concentrate whole mass on single point and calculation become easy

where centre of rigidity is the point where whole body have fully resisting against rotation.It helps in determine  how much moment need or act to rotate whole body

The center of mass of a structure represents the point through which vertical forces act and the center of rigidity represents where lateral forces act through