Centre of Mass and Gravity
The intersection of the lines is the centre of mass.
Closely related to the centre of gravity is the centre of mass. The centre of mass is moree of a geometrical concept than the centre of gravity, derived from forces. The difference is only important when the gravitational field is strong and non uniform. In this case the centre of mass will be at the same position inside the body, but the centre of gravity will be shifted in the direction of the force.