What forces are causing the COM to align with the tail end of force vector?

Question

A force F is continually acting on the end of a solid rod at a pivot point A  (see image below). The object causing that continual 'Force F' is attached to pivot point A and constrained to only move in the line of direction shown.
What forces are causing the center of mass (COM) to move in line with the tail end of the force vector F?
I understand that one can assume a ‘moment of a couple’ will be created about the COM,  but couples do not physically move the COM.  If that is the case, then is it force F causing the COM to move up and to the left?
But how can that be possible because there is no vertical force component for F?

Tony Stark · Answer

Consider Newton's Second Law -
$$∑F = m a$$
What exactly does a mean here.It refers to acceleration of Centre of Mass of the system.In your question,when you use Newton's Second Law the acceleration term is of Centre of Mass and not that of A.
Get it?
Centre of Mass does not move up. Point A moves down.Centre of Mass moves in a straight horizontal line.

Why does point A moves down?

This is because F provides necessary torque to do so.

Dubious · Answer

After much thought I think I have the answer but I had to go through various steps . Please see the diagrams below. For the COM to move up and align itself with force F it seems another force needs to be applied at point A to prevent it spinning around its centre of mass.

What forces are causing the COM to align with the tail end of force vector?

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