A rigid, vertical rod with a mass of 2.9 kg simply rests on the floor and is held in place by static friction. The coefficient of static friction between the rod and the floor is 1/7. The rod also has a wire connected between its top end and the floor, as shown in the figure. A horizontal force F is applied at the midpoint of the rod. Find the greatest force F that can be applied at the midpoint of the rod without causing it to slip. N