In this work, the forced vibrations of rigid and flexible cantilever beams clamped in one end, are studied. The experiments, in addition to illustrating the resonance phenomenon in a different structure of the classical mass-spring oscillator, permit measure the Young's modulus of the rod's material. In order to display the fundamental mode together with the second and third normal mode of vibration, we use a cantilever beam made of a less rigid material. This allows us to compare the shape of the beam when it vibrates in different modes, with the theoretical predictions. In particular one can observe the presence of "quasi-nodes" (or nodes with small amplitude) where the energy flow compensate for power loss.
normal modes; bandwidth; Young's modulus
