2 of 3
OK. as drawn, ignoring mass and accelerations, the force $$F_p$$ will appear as a torque on your ball screw.
Edit bei questioner: The point where you get stucked, is that torque is a form of energy while force is a potential. Applying Newton's third law, as suggested, $$F_p$$ is affecting the bearing with 100% - but $$F_p$$ is also moving the the mass/screw by $$x$$ and therefore introducing the energy $$F_p \cdot x$$, which is transformed into the torque $$T_p$$ ~ $$F_p \cdot x$$, which finally brakes the motor.