======Breaking Glass with Sound======


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**Materials: **{{$demo.materials_description}}\\
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**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Resonance and Glass Shattering
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====Summary====                   
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====Procedure====  
  - Select a large wine glass with thin walls and a clear, ringing resonance when tapped.
  - Identify its resonant frequency by gently tapping and listening for the pitch.
  - Position the glass in front of a strong sound source such as a compression driver and amplifier.
  - Play a pure tone that matches the glass’s resonance, starting at low volume and increasing gradually.
  - Use a visual aid (such as a small piece of paper leaning against the rim) to confirm vibration.
  - Adjust frequency slightly lower than the tap-test pitch, since resonance shifts as vibration increases.
  - With sufficient power and resonance, the glass will shatter.




====Links==== 
A MythBuster's Glass Shattering Montage - Jaime Vendera: 
{{youtube>IZD8ffPwXRo?}}\\


📄 How to breaking glass with sound - SalfordAcoustic: [[https://salfordacoustics.co.uk/how-to-breaking-glass-with-sound]]\\

====Variations====
  * Instead of a loudspeaker, use a trained singer who can hold a steady pitch near the glass’s resonance, but still amplify electronically for safety and consistency.
  * Try glasses of different shapes and thicknesses to compare resonance strength.
  * Use high-speed video to capture the moment the glass deforms and breaks.
  * Explore safe demonstrations of resonance using vibrating plates or tuning forks if breaking glass is impractical.



====Safety Precautions====
  * Only attempt with proper equipment and training; not suitable as a casual classroom experiment.
  * All nearby observers must wear safety goggles and hearing protection.
  * Keep a safe distance; broken shards can scatter further than expected.
  * Do not attempt by holding a glass near the mouth — dangerous if glass shatters unexpectedly.
  * Secure the glass in place so that fragments do not travel toward the audience.




====Questions to Consider====
  * Why does the glass break only at its resonant frequency? (Because resonance amplifies vibration amplitude until the glass structure fails.)
  * Why is a thin-walled wine glass preferred? (It has lower damping and stronger resonance, making it easier to vibrate.)
  * What real-world systems must engineers design to avoid resonance damage? (Bridges, skyscrapers, aircraft, and machinery must all avoid destructive resonance.)
  * How does this connect to the concept of simple harmonic motion? (Resonance occurs when external driving frequency matches the system’s natural frequency, maximizing oscillation amplitude.)