A few weeks back we looked at the phenomenon of resonance with oscillating metronomes. As a follow-up to that meditative and Zen-like video, we've included a crystal-clear demonstration of that favorite old opera singer's trick: shattering a wine glass with resonance.

This charming little video demonstrates the principle of resonant frequency using oscillating metronomes. The mechanical wind-up metronomes used worldwide during the dreaded Saturday piano lesson employ an inverted pendulum to keep even time intervals. The resonant frequency of the pendulum is adjusted by moving the mass up and down. Sliding the mass higher up the rod decreases the resonant frequency of the pendulum by increasing its rotational inertia.