The free and forced longitudinal vibration, undamped and damped, linear and non/linear, with 1 degree of freedom (DOF) and more DOF. The free undamped and damped vibration. The assembly of springs - serial and parallel. The forced vibration, constant force, harmonically changing force. The steady state solution, the transient solution. The amplitude and phase diagram. The centrifugal force as the cause of vibration. The force transmision into the ground. The vibration with 2 DOF, the basic features, the equations of motion, the solution. The free undamped vibration with 2 DOF, the natural frequencies and mode shapes, the modal properties. The forced vibration with 2 DOF. The anti-resonance phenomenon, the active damping. The vibration with more DOF - generalization. The free vibration - the modal properties - the modal analysis. The forced vibration - the harmonic analysis. The forced vibration - the transient solution.