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What You need to Know Energy

o Kinetic Energyo Potential Energy

Amplitude

Frequency

ResonanceResonance

- Resonance is defined as the tendency of an object Resonance is defined as the tendency of an object to oscillate or vibrate at greater amplitudes when to oscillate or vibrate at greater amplitudes when another sources emits a frequency of the objectanother sources emits a frequency of the object

- To explain it in clearer terms we take the example To explain it in clearer terms we take the example of a child on a swingof a child on a swing

Mismatched FrequencyMismatched Frequency

What happens when the What happens when the emitted frequency is lower?emitted frequency is lower?

What happens when it’s What happens when it’s higher?higher?

Mismatched FrequencyMismatched Frequency

What happens when the What happens when the emitted frequency is lower?emitted frequency is lower?

What happens when it’s What happens when it’s higher?higher?

- Mechanical Resonance is a type of resonance that deals with mechanical systems.

- A mechanical system is taken to mean a physical object.

- Bridges and other large structures are the perfect examples to demonstrate Mechanical resonance.

Nimitz Nimitz Freeway Freeway CollapseCollapse

- A bridge that was located in San Francisco, A bridge that was located in San Francisco, CaliforniaCalifornia

- Collapsed in 1989Collapsed in 1989

- The reason for collapse was an earthquake that The reason for collapse was an earthquake that struck the city.struck the city.

Soldiers on Soldiers on BridgeBridge

- Great story my teacher always used to bring up in Great story my teacher always used to bring up in high school.high school.

- Now soldiers don’t march in step while crossing a Now soldiers don’t march in step while crossing a bridgebridge

So why did it collapse?

One theory is that it collapsed due to forced resonance

Another theory is that it collapsed due to self-excitation (aero-elastic flutter)

The problem was with the design of the bridge

The bridge was closed from the sides, thus blocking the air from passing through

Engineers were able to figure this out and so it was decided that when building bridges, the sides would be kept open

Webdev17 (2009, March 2). Tacoma-Narrows Bridge construction & Collapse 1940

4 min. Retrieved December 2, 2012. From: http://www.youtube.com/watch?v=6AlSZT9k1ww

GonzoNugent (2006, September 28). Tacoma Narrows Bridge Collapse “Gallopin Gertie”. Retrieved December 2, 2012From: http://www.youtube.com/watch?v=j-zczJXSxnw

Crowell Benjamin (2012). Light and Matter. n.d. n.d.pg 443-456. Retrieved from http://www.lightandmatter.com/lm.pdf. Accessed on December 2, 2012. ( Statistical data concerning Tacoma Narrows and Nimitz freeway was obtained from this source)

K. Billah and R. Scanlan (1991). "Resonance, Tacoma Narrows Bridge Failure, and Undergraduate Physic Textbooks" (PDF). American Journal of Physics 59 (2): 118 124. http://www.ketchum.org/billah/Billah-Scanlan.pdf Retrieved December 2, 2012.(Statistical data concerning Tacoma Narrows was obtained from this source) 

"Shattering wine glass." University of Salford Manchester. N.p., n.d. Web. 2 Dec. 2012. Retreived from http://www.acoustics.salford.ac.uk/feschools/waves/wine1video.htm

Works Cited

"0.jpg." article.wn.com. N.p., n.d. Web. 2 Dec. 2012.

<i.ytimg.com/vi/d6V2YAkyEdg/0.jpg>. "Amplitude." math.ubc.ca. N.p., n.d. Web. 2 Dec. 2012. www.math.ubc.ca

/~cass/courses/m309-03a/a1/pcheng/Amplitude.jpg. "Frequency." qrg.northwestern.edu. N.p., n.d. Web. 2 Dec. 2012.

www.qrg.northwestern.edu/projects/vss/docs/media/Communications/frequency.gif.

"Nimitz_cypress_Structure."returntothe80s.wordpress.com. N.p., n.d. Web. 2 Dec. 2012. www.vias.org/physics/img/nimitz_Cypress_structure.jpg.

"Potential-and-kinetic." Petervaldivia. N.p., n.d. Web. 2 Dec. 2012. www.petervaldivia.com/technology/energy/image/potencial-and-kinetic.bmp.

"Tacoma Narrows Bridge (1940)."Wikipedia. N.p., n.d. Web. 2 Dec. 2012. <en.wikipedia.org/wiki/File:Image-Tacoma_Narrows_Bridge1.gif>.

"mum-girl-swing." oliverhume.com.au. N.p., n.d. Web. 2 Dec. 2012. <www.oliverhume.com.au/assets/mum-girl-swing.jpg>.

Works Cited

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