One end of a post weighing 400 N and with height h rests on a rough horizontal surface with Ks=0.30. The upper end is held by a rope fastened to the surface and making an angle of 36.9^\circ with the post. A horizontal force F_vec is exerted on the post as shown. (Figure 1)
How large can the force be without causing the post to slip if its point of application is 6/10 of the way from the ground to the top of the post?