Mechanical Resonance

1. Mechanical Resonance

2. Tuning Fork Example! • When objects are allowed to vibrate freely, they do so at their natural frequency

3. Resonance – the transfer of energy from one object to another having the same natural frequency • Mechanical Vibration – resonance involving mechanical systems • Sympathetic vibration – the response to a vibration with the same natural frequency

4. Wine Glass Demo

5. Every object has a natural frequency at which it will vibrate • Pushing a child on a swing at the right time (frequency of the swing matches frequency of push) • Vibrations in radio waves cause antennas to vibrate • Earthquakes/strong winds – match the frequency of a building makes it vibrate and can make it crumble – taken into consideration by architects

6. The Result of Resonance • When energy is transferred through resonance, the energy results in an increased amplitude of the vibration • If we play our music louder and louder, the windows in your room will vibrate with a greater amplitude until they can’t take it and they break

7. Countering Resonance • We use dampers • A damper removes energy from a structure by absorbing it

8. Resonance in the Body • entire body – 6 Hz • head – 13 – 20 Hz • eyes – 35 – 75 Hz • Large amplitude vibrations at any of these frequencies could irritate and/or damage parts of the body

9. Uses of Resonance • eggs exposed to ultrasound will resonate of a narrow range of frequencies • salmonella bacteria which can infect eggs cause the eggs to vibrate over several frequency ranges which can be detected • same thing used to detect the presence of biological and chemical warheads in a missile or artillery shell – don’t have to open it