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Stone Skipping the Scientific Way
Quirk writes "National Geographic has a bit on the scientific analysis of stone skipping. Using a machine launching aluminum disks Lyderic Bocquet, a physics professor at the University of Lyon, and his colleagues discovered the 'magic angle' of 20 degrees as that required to maximize skipping. 'Jerdone Coleman McGhee of Wimberley, Texas, holds the current Guinness Book of World Records title for a 1992 toss that yielded an impressive 38 bounces across the Blanco River in central Texas'"
what they'll be doing at the next foo camp ;)
USE='clever' emerge -u sig
I am horrible at skipping stones, but the best I ever got was on lake oneida up in NY right before it froze over (I think it was like 10 skips; yeah, I suck). I wonder how much the other type of degrees (temperature) effects things . . . physics/chem geek want to wax eloquent?
What we should REALLY be trying to figure out is how to skip more massive stones. That's the next step.
This one time, me and some people were skipping stones *hardcore* style. We got the biggest flat rocks we could lift and tried to spin them. Usually they just glided, but sometimes they would skip fairly high.
Of course, once the government got hold of this technology, they would put it to use bombing Iraq.
Esoteric reference.
Why do a scientific analysis of something when you ignore the #1 variable: The Stone.
...good to see tax payer/student dollars at work
Zillions of years of waves busting up the tough rocks has polished them all smooth and flat. This makes for some of the best skipping stones ever. We're talking about an endless supply here.
Some of the piles I've seen reach 3 to 4 feet in height and run for hundreds of yards down the beach; all made up of beautiful rocks. If you're lucky you can find some other nifty stuff like beach glass or driftwood. And not so nifty stuff, like dead fish and RIAA jackets.
that a human can skip one 38 times, but there is no mention on how many times the machine they built was able to do it. Just watch, this is gonna lead to some wacky robotics competition where teams try to construct different robotic launchers to see which can skip more times or longer distance.
"0101100101? It's just jibberish. *looks in mirror, gasps* 1010011010@!? AHHHHHH!!"
...geeks bringing a stone skipping machine to tweak and experiment with while they go camping with their Wi-Fi gear. Can't we have a normal camping trip? =)
My innocent childhood hobby has been ruined with the introduction of science and actual calculations! Not to mention that I've only ever been able to get like five skips. *runs to hide*
Try actually thinking for yourself. It's quite refreshing.
You centrally located people haven't experienced stone skipping until you have been to the ocean. Easy to get 15-20 skips in a calm inlet. Dense salt water makes it that much easier.
I'm sure at the dead sea you could really make 'em go.
The article suggests that this is the first time this type of problem has been scientifically studied. As far as I know this kind of problem has been very thoroughly studied for aerospace purposes: a planet's atmosphere is the pond, and a spacecraft is the stone. A google search for 'skip trajectory' shows up lots of serious research.
Warning: not for the faint-hearted!
Any disc golfer or ultimate frisbee player can tell you that changing the shape or weight of your disc can very significantly affect its dynamics. It could be that they've only found the ideal release conditions for the particular disc they were testing with.
Here is a news article in the science journal which has the original report.
Infuriate left and right
http://www.rootstrikers.org/
the allies figured this out in ww2. Nazi dam bombing
The massive spinning bombs that were designed to bounce along the water before sinking and exploding in front of a dam? That technology was developed and used successfully in world war II by the english.
I ran a benchmark on my quantum computer, now I can't find it anywhere!
I recall watching a documentary about Barnes Wallis, a British scientist who during WWII invented and "perfected" a dam busting bomb. A rather large (multi ton) spinning cylinder full of explosives that would be dropped from a plane at remarkably low altitude over water directly at a dam at high speed, resulting in the bomb's skipping, like a stone, until it would collide with the dam. The bomb would then sink, but it's spinning motion would keep it tight to the dam until it exploded.
Wallis' research involved countless stone skipping tests, that inevitably resulted in the discovery of the perfect angle.
The bombs themselves enjoyed marginal success, succesfully destroying 1 of 3 objectives, if I'm not mistaken.
http://simscience.org/cracks/dambusters.html - Interesting videos and more information.
I mean, the trailing edge is the edge that will hit the water first if you're talking a 20 degree angle, and if the stone skipped, the center of force would have to be behind the stone's center of gravity (otherwise it would sink).
If it skips soon enough, it could be far enough behind the center of gravity to cause the stone to flip. But I doubt it happens all the time, because I can't see getting it to flip the same speed every time. If it doesn't flip by about 180%, the stone would soon hit at a bad angle and sink. The chances of even getting three or four skips in a row would probably be ridiculously small, but I can get at least that many skips fairly consistently.
It isn't entirely uselsss. "skipping stones" was the tech behind the bouncing bombs in WWII that the Allies used to destroy German dams to deprive their industry of water. A couple weeks ago there was a great documentary about it on t.v. but i can't find a link - wuz on discovery or history channel i think - might have been one of those "dangerous jobs" shows. The bombs would bounce across the water & timed so that they would sink when they got up close to the dam and then detonate deep under water against the structure. Unfortunately, my words do not do the program justice.
Getting a golf ball to skip...now that takes talent. Yeah, that's it. Talent...
We recently sailed out to Ft Jefferson in the Dry Tortugas. We read where the soldiers would heat cannonballs to red hot and shoot them at enemy ships. They even made an oven with 4 magazines in it for the job. They used layers of wet and dry padding between the poweder and ball in the cannons. My pics don't say what size balls but they were one of 12, 18, or 32 lbs.
These balls would skip along the saltwater and bury themselves in the ships at waterline level where the seamen couldn't get to them. The balls would then burn through the boats hull, hopefully starting a fire.
See, there were even geeks back then with a lot of time and resources on their hands. This must have taken a lot of practice.
Also visited Fort Pulaski outside of Savannah GA. These 2 forts were designed to be very similiar in so many aspects. But there is no mention here of this kind of ball skipping. Where Ft Jefferson is surrounded by water, though, Ft Pulaski only has it near in a 45degree arc, and that's more than a 1/4 mile away. The ships channel is out of cannonball range these days; maybe it wasn't back then.
Mysterious Rock Movements
January 12, 2003
Lake Superior, Minnesota
Scientists and local authorities are struggling to explain the sudden rise in the level of lake Superior. After long investigation the rise was attributed to a big pile of mostly flat rocks that somehow made their way into a pile a few meters from the shore. There was also a smaller pile of not-so-flat rocks much closer to the shore.
Invstigators attempting to trace the people behind this strange event have only a few puzzling clues to guide them. The whole beach appears to bave been trampled by hundreds of thousands of people. The only clues to their presence is all those strange conical pieces of tin-foil with the base roughly the size of a human head. There were also a number of RIAA jackets nailed to tree stumps and impaled with darts.
Darl McBride, strangely showed up and shoved the following quote down our throats: "I'm not sure who is behind this, but I'm certain we own the intellectual property. We can't tell you quite what the property is or how it was violated, but please send us $699"
The stone is usually spinning around an axis that is more or less vertical. The angular momentum of the stone makes it much more difficult to flip over via forces exerted by the water interface. In order to have it flip over, the axis of the spin now has to become horizontal requiring a tremendous torque.
A stone fired at a lake with no initial spin might easily tumble in the manner you're describing, but probably wouldn't skip nearly as well.
((lambda (x) (x x)) (lambda (x) (x x))) http://www.endpointcomputing.com a scientific approach to custom computing.
I skip the Stones whenever they're in town.
I'm not paying $150 a ticket to see a zombie like Keith Richards.