There is no force exerted by one part on the other.
I am not sure if the second rider would exert a force on the first person.
Any other matter coming in contact with the field will feel a force exerted by it.
She had to study the situation as if it were an engineering problem, like trying to exert force in some difficult medium.
Well, the larger planets in our system exert an even bigger force.
Once they get big enough, their gravitational fields will exert a major force.
He had to exert considerable force to keep the rod from being pulled out of his hand.
The support and Earth exert force on each other.
That they exert great force upon the physical world is beyond doubt.
Let us call the force exerted by the chain on the point to which its end is attached.