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Transcript of Resonance
what is resonance?
Did you know?
Applications of Resonance
How did the Tacoma bridge collapse?
On the morning of November 7, 1940, the four month old Tacoma Narrows Bridge began to oscillate dangerously up and down. A reporter drove out on the bridge with his cocker spaniel in the car. The bridge was heaving so violently that he had to abandon his car and crawl back to safety on his hands and knees.
At about 11:00 the bridge tore itself apart and collapsed. It had been designed for winds of 120 mph and yet a wind of only 42 mph caused it to collapse. How could this happen? No one knows exactly why. However, the experts do agree that somehow the wind caused the bridge to resonate. It was a shocking calamity although the only loss of life was the cocker spaniel.
Can sound break glass?
Research has been carried out which shows that the glass needs to contain a small flaw. The shattering starts with this small crack. The blemish can be too small to be seen by the naked eye. Good quality glasses with no flaws are unlikely to break.
Opera singers have been rumoured to break glass with just their singing note. They have been trained to produce more than 100 db of volume and would have good pitch to match the resonance of the glass.
The louder the sound, the more violent the vibrations will be. When they reach a level that the glass cannot withstand it will shatter.
The volume required is more than 100 db, a level that is difficult but not impossible to reach with just the voice. Normal speech is around 50 db. In experiments, often an amplifier and speaker are used so achieve the required volume. NOTE: Damping is the way of decreasing of the amplitude of an electrical or mechanical wave.
PREPARE 1/4 SHEET OF PAPER!
The word resonance comes from Latin and means to "resound" - to sound out together with a loud sound.
Resonance is a common cause of sound production in musical instruments. It is one of the most striking and unexpected phenomenon in all of physics.
Without resonance we wouldn't have radio, television, music, or swings on playgrounds, not to mention cool gismos like Tesla coils. Of course, resonance also has its dark side. It occasionally causes a bridge to collapse, a helicopter to fly apart, or other inconveniences.
Tacoma narrow bridge footage
sound breaking glass
1.opera singers are trained to produce more than 150 db. True or false
2. objects mostly have one frequency. true or false.
3. the resonance comes from the latin, meaning "presound" true or false
13.They are rumoured to break glass with just their singing note.
14.how much decibel do a normal speech have?
15.what is the title of our presentation?
10. It is the bridge where 74 marching soldiers were crossing heading back to barracks in Salford .
11. a decreasing of the amplitude of an electrical or mechanical wave.
12. in what year did the Tacoma Narrows Bridge collapsed?
Most vibrating objects have multiple resonant frequencies.
4.-6. give 3 application of resonance
7-9. Without resonance we wouldn't have -----, ------,------- or swings on playground.
Pushing someone on a swing
Note that the natural frequency of the swing is not influenced by the mass of the person in it. In other words' it makes no difference whether a swing has a large adult or a small child in it. It will have the about the same natural frequency. Slight differences can be caused by slightly different locations of the person's center of mass. This is located about two inches below the navel.
In the bridge it can be supplied by wind, or even the periodic motion of people walking on it.
Pedaling a Bike
A vibration that's much more rapid than the turning of the wheels is usually due to resonance in the frame. You'll usually see this more often when going downhill at high speed -- the front wheel will suddenly begin vibrating violently, such that you fear losing control of the bike. What's happening is that minor vibrations in the bike (or even just due to the road) found a resonance in the bike frame, and the vibration becomes self-reenforcing due to the way it causes the front wheel to twist.
Resonance causes an object to move back and forth or up and down. This motion is generally called oscillation. Sometimes the oscillation is easy to see such as the motion of a swing on a playground or the vibration in a guitar string. In other cases the oscillation is impossible to see without measuring instruments.
Broughton Bridge had been in use about five years when it suffered a catastrophic collapse, though happily no fatalities ensued. A small column of 74 soldiers marching four-abreast was crossing the bridge heading back to barracks in Salford . The bridge began to move in time with their step. The resonance increased as they moved further across, and as they playfully timed their paces deliberately to augment the swaying movement. As the column reached the far end one corner of the structure gave way at the other throwing 40 or so of the men into the river, at that time thankfully shallow. It seems the resonant frequency they set up by their well-timed marching put stresses on a major component, breaking it suddenly.
Six of the men broke limbs in the fall, and another dozen or more suffered lesser injuries. Ever since the incident British troops have broken step as they cross bridges, avoiding the danger of resonance building up.
Did you know?
In 2005, “Mythbuster” a television show aired the first recording of voice being able to break a glass. They surveyed all different types of wine glasses before selecting the crystal wine glass due to its delicate structure. After failing 12 times, rock singer and vocal coach Jamie Vendera broke the lucky glass 13 by singing with the assisted of amplifier to increase his volume without acrostic enchantments. Showing that voice can break, however, a very loud powerful voice needs to be used.