Mechanical Waves

Resonance Every oscillating system has a natural frequency: Pendulum / mass-spring : time : period T = 1/f Pipes / stretched string : frequency of standing waves Most systems are damped by friction: e.g. pendulum comes to a halt What if we drive (or pulse) the system at its natural frequency ? (i.e. add energy): one gets HUGE oscillations. Even glass has a resonant frequency. If Engineers do not take into account resonances: The destruction of Tacoma Narrows bridge. This is actually an example of a sustained oscillation. Can you break a glass with your voice? Review What are examples of damaging resonance? Takoma Narrows Bridge (wind) buildings in earthquake (vibration) wineglass next to speaker (sound) Can we use resonance to our advantage? resonant cavities : guitar, violin, drum stereo speakers acoustics lasers (optical resonance) Resonance in: 1-Dimension = line - string 2-Dimensions = flat plane - drum head 3-Dimensions = volume - box

Ch. Elster
Aug 26 14:27:03 EDT 2019