We have been taught that the point of application is the point at which the force is applied. In contact forces, the point of application is the point of contact and in forces acting from a distance, the point of application is the center of gravity of the object on which the force is done.
So for example consider a ball hanging from a string. The force on the ball done by the string is the tension force (a contact force) and the point of application is the single point of contact between the string and the ball. So if I want to represent the force, I will have to draw an upward vector where the tail of the vector starts from that point of application.
Now consider the example of a ball fall under the effect of its weight. The force here is weight which is a force acting from a distance The point of application in this case is the center of gravity of the ball which is mathematically the center of the sphere. So if I want to represent the force weight, I will draw a downward vector where the tail of the vector starts from the center of that sphere.
Now the confusion arises when it comes to archimedes up thrust force. We know the force is a contact force, but in this case the point of application is that of forces acting from a distance, i.e. the center of gravity.
I am confused, how is that the case?