3. The square timber used as a railroad tie carries two uniformly distributed loads, each totalling 48 kN. The reaction from the ground is uniformly distributed. Determine the smallest allowable dimension b of the section if the bending stress in timber is limited to 8 MPa. Also, draw the shear force and bending moment diagrams. [Marks: 201 0.5m 0.2 m 48 KN 1.0m 0.2m 0.5m 48 KN