5. A bar AB having length L and axial rigidity EA is fixed at end A as shown in Fig. 3. At the other end, a small gap of dimension s exists between the end of the bar and a rigid surface. A load P acts on the bar at point C, which is two-thirds of the length from the fixed end. If the support reactions produced by the load P are to be equal in magnitude, what should be the size s of the gap?(20分)