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SPH 3U. Resonance & Damping. Resonance & Damping. Think of life on the swings: How do you go faster? How do you slow down?. Resonance & Damping. Swings are examples of resonance and damping
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SPH 3U Resonance & Damping
Resonance & Damping • Think of life on the swings: • How do you go faster? • How do you slow down?
Resonance & Damping • Swings are examples of resonance and damping • Damping: a reduction in the amplitude of a wave as a result of energy absorption or destructive interference • The amplitude is minimized
Resonance & Damping • All things have a resonant frequency – this is the ‘natural’ frequency • Resonance occurs when the frequency of the waves affecting the object are equal to the resonant frequency • The amplitude is increased
Resonance & Damping • Mythbusters (breaking glass)
Waves & Structures • Mechanical Resonance: When energy transfer from one source to another with the same natural resonance • Aeroelastic Flutter: When more energy is added by vibrations then can be lost by natural damping • Often caused by wind interacting with the aerodynamics of an object
Waves & Structures • Tacoma Narrows Bridge
Waves & Structures • Structures are susceptible to wind and earthquakes • Narrow streets increase wind speed • Wind can cause buildings to sway up to 1 m; earthquakes can cause buildings to exceed this
Waves & Structures • Before WWII, tall buildings were constructed with thick concrete walls, with steel bars • The concrete resisted compression, but was not flexible • The steel bars added some flexibility
Waves & Structures • After WWII, tall buildings were constructed using girders these are better able to withstand waves • The walls were not for support, but merely weather-proofing
Waves & Structures • Earthquake Dampers • Taipei Mass Damper • Discovery Taipei 101 (3/5)