Final answer:
To break a wine glass with your voice, you must sing a note that matches the natural frequency of the glass, which causes resonance to build up until the glass can no longer withstand the vibrations and shatters.
Step-by-step explanation:
To break a wine glass with your voice, you indeed need to sing a note. This is true. The concept behind this is related to resonance and the natural frequency of the glass. For this to work, the performer must sing a note that exactly matches the natural frequency of the glass. When the sound wave with the correct frequency is directed at the glass, the molecules in the glass start resonating with it. As this happens, they begin to vibrate more and more until the amplitude of vibration becomes so great that the glass can no longer withstand the stress, and it shatters.
Resonance occurs when an object is exposed to vibrations at its natural frequency, causing the object to oscillate with larger amplitudes. In the case of a wine glass, if enough energy is introduced steadily into the system through sustained singing of the resonant frequency, the structure of the glass can eventually fail, resulting in the glass breaking.