Force  and moment. Free body diagram. Equilibrium of the particle and of the rigid body. Forces distributed along the line, area forces and body forces. Equivalent systems of forces.  Center of gravity. Degrees of freedom, supports. Trusses, method of joints and method of sections. Internal forces, stresses. Strains, Hooke's law. Thermal stresses. Bending of beams. Bending moment and shear force diagrams