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snopes
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Comment: I have always heard that if a single cat were to cross the Golden
Gate bridge, that the entire bridge would collapse. It was always
something about the way a cat walks and the way the bridge suspension
works. I know this looks obvious, but my husband and I were arguing about
it today and I knew you guys would know, or at least know where to find
the definate answer.

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Dark Jaguar
We Wish You a Merry Giftmas


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Wow.... That's....

Seriously, someone actually made this up and told it to someone who bought it?

Isn't this similar to the legend about if an army marched across this same bridge it would collapse due to the vibration caused and increased by the perfectly timed marching?

Anyway, if this person wants the DEFINATE answer, grab a cat and go on a trip. That'll do it right there. Oh, I'm sure whoever in this argument is FOR it will say "you would risk lives, not to mention billions of dollars of engineering, just to prove a point?", but here's the thing, it's not a risk at all since it's NOT TRUE [Big Grin] .

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felineki
The Red and the Green Stamps


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I heard this one in my Physics class, however not so much as something that supposedly happened, but rather as a symbol of the effects of natural frequency.

Vibrations can cause damage, that's what allows opera singers to break glass with their voices and such. However, I doubt that the vibrations caused by a single cat's walking would affect a bridge.

We did watch a video of one bridge that began to sway wildly and eventually collapsed due to vibrations caused by wind, IIRC.

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Four Kitties
Layaway in a Manger


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quote:
Originally posted by felineki:
We did watch a video of one bridge that began to sway wildly and eventually collapsed due to vibrations caused by wind, IIRC.

Tacoma Narrows Bridge collapse

--------------------
If swimming is so good for your figure, how do you explain whales?

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Silas Sparkhammer
I Saw V-Chips Come Sailing In


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Small forces, delivered in exact tune with the fundamental frequency of a structure, can add up, creating standing waves that will damage the structure.

However, structures are able to dampen out forces smaller than a certain threshhold.

For example: find a sapling in a forest, a tree maybe 20 feet high and four inches in diameter. Shake it. Pull, push, pull, push. In time, you will feel out its natural frequency of swaying, and you can get it to whipping back and forth with a very impressive amplitude.

Now...go and try that with a forty foot pine tree that's 18 inches across at the base. Old Man Pine is just gonna laugh at you. You don't have the strength even to *start* the process moving, although gusts of wind, if they came in exactly the right frequency, could.

A Caterpillar Tractor, banging into one of the main towers of the Golden Gate Bridge *might* be able to start it swaying (although, actually, I doubt it.) A Felis domesticus? Nope.

Silas

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Dark Jaguar
We Wish You a Merry Giftmas


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Yeah, I don't doubt the power of vibrations, but you have to start out with enough energy to get it going, and keep it going. The wind didn't need much, relatively, but it still needed what it gave to do it.

Considering the sheer bulk of a bridge, I don't even think a tractor could put any real dent into it.

And about that army thing, how big an army are we talking here? Maybe if the ENTIRE bridge was packed in as tight as they could get the formation... I dunno, I'm not sure how much force a soldier stomp produces so I couldn't say how much a million would produce...

I will add that cars produce a bit of a vibrational effect on the road which wears it down just a bit, and due to those existing points of wear, later cars are foced to synch up with that break down, until eventually you have all these grooves in the road that shake up YOUR car by a pretty aweful degree.

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mrrentalshoes
Deck the Malls


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They actually tested the army myth on Mythbusters and found that by the time you had enough force to sustain any kind of harmonic motion, the force and weight on the bridge were actually doing the damage to the bridge before the waves could grow large enough to do any damage.
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Malruhn
The "Was on Sale" Song


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Oh, yeah, a cat'll do that.

And if every resident of China jumped off of a platform exactly 0.88 meters high at the same moment, the resulting shockwave would throw much of the Pacific Northwest of the US into orbit, being torn right from the Earth (Terra Infirma, as it were).

And people like this are able to breed... Jesus H. Christ on a popsicle stick...

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Opinions aren't excuses to remain ignorant about subjects, nor are they excuses to never examine one's beliefs & prejudices...

Babies are like tattoos. You see other peoples' & they're cool, but yours is never as good & you can't get rid of it.

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ASL
We Three Blings


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I think jumping Jesus on a pogo stick would be a more apt exclaimation.

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"Dear Lord, please protect this rockethouse and all who dwell within..."

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ranran yousei
The Red and the Green Stamps


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I'd be more concerned about the damage a cat could have on traffic. One car serves to miss it, chaos ensues.


ranran "I'll sell you this bridge at a price too good to be true" yousei

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First of Two
The Bills of St. Mary's


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quote:
Originally posted by Malruhn:
Oh, yeah, a cat'll do that.

And if every resident of China jumped off of a platform exactly 0.88 meters high at the same moment, the resulting shockwave would throw much of the Pacific Northwest of the US into orbit, being torn right from the Earth (Terra Infirma, as it were).

And people like this are able to breed... Jesus H. Christ on a popsicle stick...

*crumples paper*

Scratch Diabolical Plan #87204...

*grumble grumble*

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"Liberalism is a philosophy of consolation for western civilization as it commits suicide." - Jerry Pournelle

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Real Hair
The Red and the Green Stamps


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I heard that a cat walked across the pentagon; it was not hit by a plane

[fish]

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Brian O'blivion
Deck the Malls


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Yeah, but what if an army of cats crossed a bridge?

What if an army of cats urinated on a bridge?

http://story.news.yahoo.com/news?tmpl=story&u=/afp/20041127/od_afp/indonesia_bridge_urine_041127072530&e=3

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JFB
Jingle Bell Hock


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Vibrations don't kill people on bridges, but rumors can.

In 1883, a panicked crowd stampeded off the Brooklyn Bridge promenade when word spread that the bridge was about to collapse. Some argue that the bridge may have swayed, but only within its design parameters. 12 people were killed, all trampled by the crowd.

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Elwood
Little Sales Drummer Boy


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My high school band director, who was usually very insistant that the band *always* stay in formation when in uniform, would have us break formation and walk normally rather than march when crossing one of the town's larger bridges during parades. I always thought it was to give us a break, but thinking about his general temperament I now wonder if he was the victim of a UL.

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"If I didn't see it and didn't know it was a real news report, I wouldn't believe it. I mean, how nutty can you get?"-Pat Robertson Oct 26, 2006.

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Cervus
Ding Dong! Merrily on High Definition TV


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quote:
Originally posted by felineki:
Vibrations can cause damage, that's what allows opera singers to break glass with their voices and such.

Is this actually true? I always thought it was a myth.

I guess I can look it up for myself, though. [Smile]

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"There is no constitutional right to sleep with endangered reptiles." -- Carl Hiaasen
Won't somebody please think of the adults!

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Silas Sparkhammer
I Saw V-Chips Come Sailing In


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quote:
Originally posted by Cervus:
quote:
Originally posted by felineki:
Vibrations can cause damage, that's what allows opera singers to break glass with their voices and such.

Is this actually true? I always thought it was a myth.

I guess I can look it up for myself, though. [Smile]

It works best with "crystal" glass -- the kind you rub the rim of to get a nice tone. Opera singers are popular for this purpose, both for the sheer volume of their voice, and for their ability to match and hold an exact pitch.

It can be done. (I do *not* know if the "Live or Memorex" demonstration was real, however.)

Silas

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JFB
Jingle Bell Hock


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More common is the kind of singing that compels cats to flee across bridges, causing those bridges to collapse.
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