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The Breakdown: Tongue Deadlift
Thomas Blackthorne has performed numerous impossible acts over the years, including swallowing swords and even a jackhammer, so the idea of lifting 25 pounds with his tongue probably didn't intimidate him all that much. The tongue itself doesn't actually look like it's doing the lifting; it's not like he's doing bicep curls here. To actually raise the weight off the ground, Blackthorne appears to be engaging his lower back muscles, keeping his arms out to the side to stay balanced. The main job of his tongue, therefore, is to stretch and hold without snapping. (Which would make for some nasty video.) The tongue itself is mostly muscle. Some of those muscles are charged with altering its shape, others with keeping it attached to the floor of the mouth and back of the throat. Both sets are probably stretched to near the tearing point here. After looping a hook through his tongue, then attaching the chain to the hook, Blackthorne lifts the box, and the intrinsic and extrinsic muscles, which anchor the tongue, stretch but hold tight. Of course this should go without saying, but we'll throw it ou there anyway: Please don't try this at home.—Gregory Mone
Talk about thirsty. The water-gulping feat in the trick shown here doesn't quite demonstrate Kobayashi-level skill, but it's still a shock to watch. In a tremendously un-scientific test, we determined that it would normally take about 12 seconds for the water to empty out of a similarly-sized bottle held upside down. This drinking champion does it in under five.
The plastic bottle is critical. If he were just holding it upside down, gravity would be doing most of the work, and that's just not fast enough. Instead, he squeezes the plastic bottle, forcing half the water out. Next, he wisely pauses for a moment there in the middle of his chug, allowing air to creep up through the water and into the space between the new, lower water level and the interior bottom of the bottle. Without that, the pressure exerted would be too great - he wouldn't have been able to overcome it and suck down that last bit of water. So he lets the air flow up, lets the bottle expand and regain its normal, uncompressed state, and then crushes it again, forcing that final enormous gulp down his throat. A champion indeed.—Gregory Mone
Famed stuntman Evel Knievel died last week at the age of 69. The renowned daredevil, who said he had 15 major operations to repair broken bones and other traumatic injuries, first became famous by jumping 151 feet over the fountains outside Caesars Palace in Las Vegas, finishing with the fantastic crash seen in the clip here.
He once said that landing was the hardest part of his jumps, and that's obviously evident here. He gets the slope of the takeoff ramp right, and accelerates enough to carry him across to the landing ramp, but then loses his balance. Unlike the practioners of parkour, who enter into tight rolls to absorb the shock of landing, Knievel flips over and lands fairly flat on his back. He's just moving too fast. After this initial crush, all that momentum he built up on the bike continues to carry him forward, slamming his head into the pavement. Watching this video, it's amazing to think that he lived as long as he did. There are several great obituaries honoring his amazing and thoroughly unique life. My favorite quote: “I knew I could draw a big crowd by jumping over weird stuff.”-Gregory Mone
If you saw the most recent James Bond movie, Casino Royale, you might recognize the sport of parkour. It involves amazingly acrobatic, spontaneous physical feats, often performed in an urban setting. And although it looks like it's straight out of the superhuman stuff of The Matrix or Spiderman, it is very real. Its practitioners leap from rooftop to rooftop, scale walls and backflip over obstacles.
Watching a clip like this one, it's tempting to think there's some deft camera work at play, or some skilled CGI action, but these people are really just taking advantage of basic physics. They're taught to respect the laws of motion: They often roll when landing on a hard surface to reduce the impact on their legs and back. They take advantage of momentum, too, using body movements to transfer horizontal force into vertical when switching from running towards to scaling a wall. Similarly, they kick off walls to get a little higher and perhaps reach a ledge they couldn't have grabbed with a straight jump. Naturally, physics also gets them back now and then. Though you're not likely to catch too many slip-ups on the popular web videos or TV commercials featuring parkour and its variations, these guys are human: Friction and gravity don't always cooperate, and they do fall now and then.—Gregory Mone
Please, please, please don't try this at home. In this clip, a Lithuanian brother-sister team, both illusionists, goes for a few breath-holding records—the significant one appears to be thirteen minutes and 42 seconds at the start. To hold your breath for a long time, you need to slow your heartbeat significantly. If your heart's not working as hard, then it's not going to burn up the limited supply of oxygen in your blood as quickly. In the same way, the less you do while holding your breath, the better. Eventually, when things start getting ugly, the heart stops sending as much oxygen to the extremities, and focuses on keeping the vital organs stocked with blood. Obviously this pair is keeping these points in mind: You can see that the twins are completely relaxed, their faces not even moving, throughout most of the video.
And the chains? Sorry, can't make sense of those. In the end, the brother appears to hold his breath for more than 15 minutes, and the sister stays under for just a few minutes less. Apparently the pair inhaled pure oxygen before the start, which disqualifies them from the official free-diving record, but surely someone's got to recognize the feat. Then again, who knows what really went on. They are, after all, illusionists.—Gregory Mone
What we're seeing here are two solid-state Tesla Coils, each running in the 41 kHz range, performing a little concert thanks to some ingenious electrical work. The coils, which have been nicknamed the Zeusaphone, were developed by Tesla enthusiasts Jeff Larson and Steve Ward.
On his site, Larson explains that a particular version of this type of coil can be good for audio modulation because it produces several hundred sparks per second. The apparently continuous crack of light we see is actually a series of brief sparks. Larson and Ward figured out a way to modulate this frequency digitally, and get the sparks to crank out the sound waves or musical notes they want.
This concert features "Dance of the Sugarplum Fairies," but they've also done the theme from Super Mario Brothers and others. In terms of audio quality it doesn't quite measure up, but when you're talking pure spectacle, this has to be tops. You wonder if Tesla himself would be proud.—Gregory Mone
Even Michael Jordan would have to be impressed with this dunk. The athlete (?) in this very popular video clip apparently breaks the world-record for a trampoline-aided, long-distance dunk, soaring more than 20 feet before slamming it through. That's outside the college three-point line, MJ.
The secret to his success, according to physicist Len Fisher, an Ig Nobel winner who runs a website focused on the science of everyday life, is the leap forward towards the front of the trampoline, right before he flies to the hoop. He's not merely closing the gap here. In the middle of the trampoline, he's stretching all the springs on the outside equally, but once he moves to the edge, he really only stretches the springs closest to him. "The closer to the edge," Fisher says, "the more effective the recoil is going to be." And since he tilts his body forward, that recoil throws him horizontally.
The amazing thing, Fisher adds, is that he doesn't slip when he pulls off this switch between vertical and horizontal motion. You'd need incredibly high friction between your feet and the trampoline. Fisher wonders if he had some sort of resin that gave him a better grip. And the look of tension on the face of that guy with the glasses? Sorry, we can't explain that one. But it might just be the highlight of the whole clip.—Gregory Mone
Apparently classic cars aren't enough of a draw anymore. The Mercedes-Benz Museum in Stuttgart, Germany turned its smoke ventilation system into a spectacle, generating what the Guinness World Records organization is calling the world's largest artificial tornado. (See the November issue of Popular Science for an article about an engineer who thinks these man-made vortexes could be used to generate electricity.)
Though towering, the twister probably isn't dangerous. It's not going to suck up any bystanders, or cars. To create the effect, the museum's designers set up a disco smoke machine, then activated a set of 144 nozzles on the ceiling of the building's enormous atrium. The ventilation system, designed for emergencies, sucks the disco smoke up from below. To produce a spinning vortex, however, they blew air in from the sides, forcing the smoke to swirl.
The process took seven minutes, but the result, seen here, certainly looks capable of drawing crowds. Or making them run for their lives.—Gregory Mone
This little party trick is guaranteed to impress, and you don't need any special materials, just a decent freezer and a bottle of beer. Emory University physicist Sidney Perkowitz, the author of the forthcoming book Hollywood Science, says the phenomenon at work here is most likely supercooling - a process by which water can remain in a liquid state below its freezing point. It's a delicate balance, though, as the water will turn to ice given the slightest shock.
If supercooling is the culprit, the hidden scientist in this video most likely left the bottle in the freezer long enough for it to drop down below the freezing point - some other sites recommend about 30 minutes. Next, the shock of slamming the bottle on the table jolts the beer, and this added energy forces it to crystallize into ice.
Of course, it's hard to say for sure what's happening in this clip, and the many other frozen beer related videos posted on YouTube, because we don't have all the information. The best way to test the idea would be to try it yourself. I'd do the same, but I don't believe in waste.—Gregory Mone
This extended rubber-burning session was performed in honor of the classic Burt Reynolds movie Smokey & The Bandit, but NASCAR drivers are also prone to peeling out after a victory. So, what's at work here? We asked University of Nebraska physicist Diandra Leslie-Pelecky, the author of a forthcoming book called The Physics of Nascar, to tease out the science in the clip, and she says it's basically a big, loud, smoke-filled demonstration of the law of conservation of energy.
Normally when you step on the gas in a rear-wheel drive car, the front tires roll, and the car goes forward. Here, though, the driver also keeps one foot on the brake. The front end of the car is trying to stay in place by keeping its wheels locked, while the back end is trying to drive forward. Some of the energy the engine produces still goes into moving the car around that parking lot, but a lot of it is also lost to sound and smoke.
The asphalt itself eats away at the tires like sandpaper smoothing out a piece of wood. "You're seeing the person burning off their tires, basically," Leslie-Pelecky says. While this display is pretty impressive, NASCAR drivers produce even more smoke than this adventurous driver because their tires don't have tread. Since the tires are smooth, there's more material in contact with the track, so they burn more rubber, faster.
The final lesson? "If you try this at home," Leslie-Pelecky says, "You'll probably need a new set of tires."—Gregory Mone
You can't really expect good things to happen when a 305-pound football tackle's knee rams into an opposing player's head, but this clip from one of last Sunday's games is particularly chilling. In the video, Miami Dolphins quarterback Trent Green tries to block defensive tackle Travis Johnson as he pursues one of Green's teammates. The problem here is that Johnson is a very large and very fast man. Green realizes that throwing his 200-pound frame into Johnson's chest won't do much, so he tries to undercut the defender. Unfortunately, his timing is terrible.
As Green throws himself forward, Johnson's right knee comes up at the same time, slamming into the side of the quarterback's helmet. This is where inertia comes into play. Inside the skull, the brain is protected from minor impacts or jolts by a thin layer of fluid. In that instant after Green's head meets Johnson's knee, his helmet and skull stop moving, but his brain keeps going until it bumps up against the inside of his head.
The science of concussions is still being worked out, but there's some evidence that the momentary jarring of the brain affects blood flow. The good news: As Popular Science reported in our August issue, new helmet technology could enable scientists to get a better sense of the biomechanics of concussions, and aid coaches and trainers charged with determining whether or not a player should check back in after a mind-fuzzing hit.
For Green, though, this wasn't even a question. He was done for the day.—Gregory Mone
As far as meaty physics goes, The Bourne Ultimatum is a standout among action flicks. Compared with other pillars of the genre, like Mission Impossible and XXX,Bourne sustains some impressive dramatic excitement without succumbing to the patently ridiculous.
It's not hard to suspend disbelief during the movie's dizzying quick cuts, but Jason Bourne's Superman-like physical capabilities are a little suspect. He has astonishing reaction reflexes, infinite physical stamina, and the ability to withstand an amazing quantity of forceful blows, impacts and collisions without sustaining much more than a few scratches and an intermittently gimpy leg—pretty unlikely stuff, even for an elite assassin.
But we're not here to criticize the improbable. Why else do we go to action movies, after all? That said, there is one interesting physics moment that I feel obligated to point out: a motorcycle chase scene in which Bourne tries to prevent a CIA assassin from snuffing out the closest thing he has to a romantic interest. While taking a short cut, Bourne jumps his motorcycle over what appears to be a six-foot concrete wall. Fans of XXX may not bat an eye—Vin Diesel's grasshopper-esque, unassisted leaps over a 30-foot fence, a guard tower and a house, all without the assistance of a ramp of any kind, make Bourne's paltry six-footer look like a bunny hop. Nevertheless, it's worth taking a look at the numbers. Just how much force must he be capable of exerting on the ground to get him over the wall?
Robots are very good at doing the same thing over and over again, with ridiculous precision. They don't get bored and, as long as you keep the power on, they don't get tired, either. Still, it's pretty startling to watch the industrial arm in this clip toss in mid-range jump shots with such ease.
The arm, manufactured by a company called ABB and normally used on auto assembly lines, has been touring the country's science museums for more than ten years. Modified and programmed by a group at the Carnegie Science Center in Pittsburgh, PA, the robotic arm scoops up each basketball with two long metal rods, or tines. Then it executes one of a few pre-programmed motions—a scoop shot, a hook and a standard jumper—rolling the ball off those artificial fingers and tossing it skillfully through the rim.
But Tom Flaherty, the Director of Exhibits, Facilities and Operations at the Carnegie Center, spearheaded the development, says the robot isn't 100 percent accurate. Not because of a mechanical or software glitch. The robot runs through the same steps with each shot, but the ball itself can change. The robot is programmed to sink shots using a ball with certain specifications. If one of the balls is deflated slightly, its flight pattern might be different, and it might not slip through the net. Which really doesn't seem all that different than those NBA players complaining about the league's new basketballs at the start of last season.
Apparently all good shooters, men or machines, are picky.—Gregory Mone
This clip of a 4X4 speeding up a ridiculously steep face looks like a once-in-a-lifetime accident, but dune-climbing is actually a sport. Tens of thousands of people show up for events like this in the United Arab Emirates and other sandy locales. The driver of this vehicle undoubtedly has a serious combination of guts and skill, but apparently there's nothing all that special about the car.
Everything but the engine, and the driver who's gunning it, wants this car to roll back down the hill. Gravity in particular. The key here is momentum, which is a function of mass and velocity. Basically, the driver needs to get the car flying before hitting that slope. Once he starts heading up, he probably downshifts, since he wants to keep his RPMs as high as possible as the car starts to climb, and retain some of that momentum. The tires on the car are probably deflated slightly, too. This increases the surface area over which the weight of the car is distributed, and makes it a little less likely to sink into the sand. Just how steep is the slope? Our viewing angle tricks things up a bit. You can see once the car nears the top that the slope's not quite as vertical as it looks from a distance.
Towards the top, the fact that the driver flips, then rights himself, is absolutely amazing. There's clearly a mixture of luck and skill involved here, but he's helped in his descent by the fact that most of the mass, and the momentum, is carried up front. The car wants to go down head-first.
Hydrofoil surfing is just one of those things that doesn’t look right when you see it for the first time. These guys are surfing, riding down the face of a wave, and yet the board itself is more than a foot above the surface. Huh?
In this video, the foil is attached to the bottom of the board via a single strut. After a jet-ski pulls the surfers up to speed, allowing the hydrofoil to push board and rider up out of the water, they let go of the tow rope and let the power of the wave take control. Terry Hendricks, a physicist and long-time surfer who has designed an innovative wave-rider of his own, says the foil effectively acts like an underwater glider. When the surfers are coasting down the face of the wave, the water itself is rushing upward, getting sucked up by the energy of the swell. This rushing water acts like an updraft in the air, generating lift—only in this case it’s keeping the foil flying instead of a glider.
The real trick, though, is balance. Hendricks compares the form of hydrofoil surfing practiced in this video to riding a unicycle. The rider is balanced over that single strut, and there are probably 30 inches between the bottom of the board and the foil below the water. His own model uses two foils, front and back, and a bodyboard approach. The rider lies down, kicking into the wave. This makes it easier to balance but produces a much bumpier ride, since the leading foil stays at water level. With the surfers shown here, on the other hand, the single foil is a good distance below the surface most of the time, so they’re completely avoiding wind chop, and smoothly cruising down the face of waves that look like mogul hills. Ready to try it out?—Gregory Mone
The nearly 6,000-foot-long Tacoma Narrows Bridge, known as Galloping Gertie, opened up on July 1, 1940, and collapsed just four months later. Winds reached 42 miles per hour on that fateful day, which proved too intense for the structure. There were a number of causes, but the basic problem was that engineers hadn't yet learned to account for wind loads in their designs. During the planning phase, the engineers reduced the proposed depth of the concrete and steel girders beneath the roadway from 25 to 8 feet. This loosened the stiffness of the road, and made it much more susceptible to wind. In fact, before the collapse, local residents had noticed that less intense gusts could cause the bridge to move. But those movements involved longitudinal waves – one end of the bridge rose, the other fell, in a less dramatic fashion than what we see in one of the early scenes in this clip.
Prior to the collapse, though, the wind induced torsional movement. In other words, the road started to twist. While the center line stayed stable, one side of the roadbed rose and the other dropped. When this twisting motion peaked, the sidewalk on one side was 28 feet higher than the opposite one.
Eventually, this twisting motion proved too much for the structure. The cables started to snap, and chunks of the bridge fell into the water below. Finally, the entire center collapsed. With this mass gone, the sections on either end sagged dramatically, dropping more than 40 feet. Nowadays wind-tunnel testing is fairly standard for bridge designs. When engineers drew up the plans for Gertie’s replacement, which has been standing for more than 50 years, you can bet they spent a lot more time factoring in the breeze.—Gregory Mone
This video of legendary climber Dan Osman looks downright impossible. The camera has to be tilted. And the playback must be in fast-forward mode. There’s no way someone could scale a cliff that quickly, right? Actually, Osman’s Spidey-like ascent is the real thing. And in rushing up that rock, he demonstrates both the incredible capabilities of the human hand and the importance of not trying to test the laws of physics. First of all, friction is your friend in rock climbing, and during one close-up you can see that Osman is wearing very flexible, grip-enhancing shoes. The flexibility of the soles is critical because it puts more of the rubber sole in contact with the rock, increasing the friction, and the chances that his foot stays planted in place.
The rock itself, known as “Bear’s Reach,” would be considered an easy one for experts, offering numerous cracks and bumps and ledges large and small. In other words, Osman’s not climbing up a smooth wall. And when he’s jamming his fingers into one of those cracks, or grabbing a ledge, he’s basically proving that our evolutionary ancestors swung from branches. There’s no other good reason for our hands to be that strong, and capable of supporting so much weight. By pressing his fingers down on some exposed rock, Osman engages more of the muscles in his forearm, allowing him to bear more weight on that hand.
Obviously he’s also in ridiculously good shape. One Web site says the climb should take about three hours. In this video, Osman does it in 4 minutes and 25 seconds. Tragically, though, this daring approach to nature’s dangers led to Osman’s early death in 1998, at the age of 35.—Gregory Mone
Note to the Reader: For those of you who haven't seen Fantastic Four:
Rise of the Silver Surfer, yet are serious enough about it that you
want even the most trivial plot details kept secret until you actually
watch the movie, what follows will be a bit of a spoiler. (A rough
calculation makes us think there are about three of you out there.)
For the rest of you, don't worry, this little detail won't ruin
anything.
So, Reed Richards, aka Mr. Fantastic, is sitting in his lab trying to
think of a way to separate an alien from his cosmic surfboard when he
gets an idea. "A tachyon burst!" he exclaims.
Fast-forward a few scenes. A series of devices capable of delivering
said burst are built, one is activated, and the aforementioned alien,
known as the Silver Surfer, is cleanly knocked from his board.
Now, would this really work? Tachyons are theoretical particles
believed to travel faster than the speed of light. Trying to think
about what effect they would have on a liquid-silver alien can be
thoroughly mind-bending—would they send him back in time or even
arrive at their target in the past, thus having no effect whatsoever?
So, we appealed to University of Washington physicist and science
fiction author John G. Cramer, who has the scientific and imaginative
chops to handle such questions.
First, Cramer notes that knocking the surfer off his board would
require a transfer of momentum. And while the momentum of the
hypothetical tachyon beam would be relatively small, there might be
another, more dramatic effect. "The delivery of energy would be much
more efficient than the delivery of momentum," Cramer says, "so it
seems more likely they would blow the Silver Surfer apart rather than
knock him around."
Instead, Cramer proposed another, decidedly less-sexy idea. "I think a
cannonball or an artillery shell would work a lot better."
So, Mr. Fantastic, next time you try to save the world, do it the
old-fashioned way.—Gregory Mone
Of all the phenomenally difficult, profoundly asinine ways to get into the Guinness Book of World Records, this high-dive-into-shallow-pool feat has got to be one of the worst. Me? I’d rather walk backward for a while, à la Cliffy in Cheers, or try to master one of those balancing-balls tricks.
That said, someone did put a little bit of thought into this setup. First, there are a few sequences in the video that afford a wider view of the glorified kiddie pool and reveal that the base is a cushioned mat of some sort. This proves critical: If you watch closely, you can see the jumper bend his knee just before impact. His knee enters the water like a wedge—albeit a rounded one. If that was a real floor underneath the water, he wouldn’t have been capable of standing up and throwing that double-fisted pumper at the end.
Second, aside from that knee drop (undoubtedly a last-second effort by the diver’s brain to abort), he does have fairly perfect technique. University of Virginia physicist Lou Bloomfield says the belly-flop posture is the key to stopping short in that shallow pool. “For him to avoid injury, he has to use as much of his surface as possible to get rid of his downward momentum,” Bloomfield says. “A good belly slam helps.”
One thing science won’t be able to tell us, though, is why he’s wearing that god-awful unitard. —Gregory Mone
Ah, so that's what they teach you in those Buddhist monasteries. Meditation? A clear mind and heart? Whatever. To achieve oneness with the universe, you need to learn how to stick a rice bowl to your stomach.
The miniature monk in this clip has two things working in his favor: his munchkin-like stature and basic physics. By sucking in his midsection, then pressing the bowl to his stomach, he creates a partial vacuum in the space between the bowl's inner surface and his skin. Since the seal is tight and there are fewer molecules of air per cubic inch inside the bowl/stomach space than there are outside, the bowl sticks.
Now, as for how it stays there while he's being lifted clear off the ground, that's where the apparent lack of McDonald's hamburgers and soda in his diet factors in. Let's assume he weighs about 50 pounds, and the bowl covers about 30 square inches of his belly. In this case, University of Virginia physicist Louis Bloomfield explains that for the seal to hold, the boy only has to reduce the air pressure inside the bowl by a little more than 1.6 pounds per square inch of bowl-bound skin. (Which shouldn't be too hard.) That way, the pressure force pushing him upward against the bowl will reach 50 pounds, balancing the downward pull of his own weight.
Add a video and presto, millions of people across the world get to watch him hanging inverted and upside down, while staring at their monitors thinking . . . huh?—Gregory Mone
It breaks faster than a Mariano Rivera cutter. It's harder to hit than Rick Vaughan's fastball in the movie Major League. The gyroball is so elusive, in fact, that some speculate that it might not even exist. The gyro, which originated in Japan, is causing consternation in American baseball broadcast booths these days. But since science is fairly used to dealing with things that may or may not exist (extra dimensions, anyone?), we figured we'd give it a look.
This video shows Daisuke Matsuzaka, the new Boston Red Sox hurler, supposedly striking out a batter using the gyro. Before we get into how it works, let's look at two other popular pitches. For a normal fastball, the pitcher puts backspin on the ball, so air flows faster above the ball than it does below. The ball doesn't drop as quickly as it would if it were following a normal, gravitationally influenced path, so the batter's brain gets the impression that it's rising. And... he whiffs.
A curveball has the opposite effect: Topspin causes it to fall faster. And again, if all goes well, he whiffs.
The gyroball is said to move with a bulletlike rotation that prevents it from dropping like a curve or staying high like a fastball. In effect, it's a fastball that listens to gravity, following a trajectory unaffected by turbulence in the air.
Japanese scientist Ryutaro Himeno is widely credited with creating the pitch using computer simulations [see the published paper and video clips of the computer models here] with the help of baseball instructor Kazushi Tezuka. They published their work in a book, currently available only in Japan, called The Secret of the Miracle Pitch.
As for whether Dice-K, as he's known in the U.S., is actually throwing a gyroball in this video, that's hard to tell. Following Occam's Razor, the easiest way to find out would be to just ask him, right? That's not so easy, though. Numerous interviewers have tried to do just that, but he’s played coy, allowing the miracle pitch to remain a mystery. —Gregory Mone
A father and his two teenage children drowned when this cavernous pit swallowed up several buildings in the Guatemala City barrio of San Antonio. The hole, which appeared on February 22, is approximately 100 feet wide and 200 feet deep.
Reeking water, still swirling in the bowels of the hole, offers a telltale clue to what happened: Sewage flowing from an eight-foot-wide ruptured sewer main at the bottom of the hole eroded ash and pumice layers deposited by ancient volcanic eruptions. The leaking liquid created a shaft that grew upward through the soft ash by a process called “piping.”
Eventually the shaft became so large that it could no longer support the upper layers of earth, which abruptly collapsed into the empty space. Recent rains in Guatemala City probably contributed to the collapse by weakening the surface soil and adding storm-water runoff to the percolating sewage. Ric Finch, a retired Tennessee Technical University geology professor who has done field studies in northern Central America, has not visited the site but has examined photos of the collapsed shaft. He says the shaft’s walls contain easily eroded volcanic materials, which are found throughout the valley where Guatemala City is located. The shaft may have developed very rapidly, Finch says.
Where did the eroded materials go? Mostly likely, they were washed downstream through the partly blocked sewer main, which is more than eight feet in diameter. The bodies of the two drowned teenagers were found in a nearby canyon where the sewer system discharges.
Many news accounts have referred to the collapsed shaft as a “sinkhole,” but that is not the correct term here. Sinkholes form in places where the underlying layer consists of limestone or other soluble rock, which dissolves in water rather than simply washing away like ash. Geologic maps for Guatemala City indicate that any limestone in the area of the cave-in would be located well underneath the volcanic deposits.
Limestone-associated sinkholes are common in other regions of Guatemala (and in Florida). It’s uncommon, however, for a sinkhole to be as large and deep as the Guatemala City pit. Holes in the ground sometimes open up without warning, but not in this case. Neighbors reportedly heard noises and felt tremors for weeks before the collapse.
Some 200 residents have been evacuated from the San Antonio neighborhood, and officials have cordoned off the area around the shaft. Tom Miller, a geologist at the University of Puerto Rico who has visited the hole, says that it is slowly enlarging. Officials have used a remotely controlled camera to examine the damage, and are currently attempting to re-route the sewage. “The neighborhood does not smell pleasant,” Miller says.—Dawn Stover
You may be asking yourself, "How in the world did this woman balance on a Y-shaped rod and shoot an arrow with her toes, while bent like a pretzel?" and "Why is David Hasselhoff still on television?" Contemplating the latter question gives me the shivers, frankly, so let’s focus our attention on the Spandex-clad archer, Lilia Stepanova. There are a number of factors at work in this stunt but Lilia’s Gumby-like maneuvers basically boil down to genetics. On the extreme and improbable end, Lilia may have been born with a rare genetic defect, such as Marfan syndrome or Ehlers-Danlos syndrome, that prevents her body from building adequate amounts of collagen—the tough, stringy fibers that strengthen cartilage, tendons and other kinds of connective tissue, such as bone.
Collagen is essentially the glue that holds us together. While having less of it may be handy for shooting arrows with your feet, it’s undesirable for maintaining bone, muscle and joint health. Symptoms range in severity but typically include hyper-mobile joints, thin, stretchy skin, easy bruising and scoliosis. Lilia obviously exhibits extra rubbery joints and tendons, as evidenced by the leg that bend backs at 180 degrees, the foot that rests comfortably beneath her chin and the spine that bends like a microwaved Twizzler.
Aside from that, though, our 19-year-old Moldavian (she’s Eastern European but lives in L.A., in case you were wondering) appears to be in exceptional shape. According to her MySpace page, Lilia enjoys a fulltime career as a contortionist and dancer, which suggests that she is endowed with a milder, less harmful genetic quirk that gives her soft, pliable muscles (notice the lack of bulk or tone) yet spares her the nastier side effects associated with more severe forms of hypermobility, such as chronic pain.
Beyond the bendiness displayed by Ms. Stepanova, there are also two other factors at play: balance and coordination. The former requires both skill and a trick of physics called “center of mass” (discussed here, in a prior "Breakdown" post). By engaging a series of muscles in her arms, abdomen, back and thighs, she is able to stack her body weight neatly over the point of the rod she’s balancing on. From there, proprioception takes over to allow her to maintain balance and shoot a perfect bullseye.
Proprio-huh? The word “proprioception” refers to a cluster of nervous-system functions that help the body to understand spatial relationships and coordinate the movements of muscles accordingly, whether—in this case— for imperceptibly shifting to maintain her crazy handstand, or for zeroing in on an archery target. Some people are gifted with better proprioception than others (Tiger Woods’s must be fine-tuned to allow him to play golf so well), but it’s possible to sharpen your proprioceptive sense with exercises like juggling, balancing on a wobble board, or practicing yoga.
If you’re looking to impress David Hasselhoff with a stunt like Lilia’s, don’t lose hope: she wasn’t born an expert foot archer. Genetic advantages or no, developing her levels of flexibility, balance and aim no doubt required intense practice. And a fishnet half-shirt. —Nicole Dyer
Good thing the cars in this video are all moving slowly. Add a little more speed, and the scene would be a driver’s worst nightmare. Imagine a car pileup in front of you on a snowy day, your own skidding wheels and, seconds later, the inevitable crash…
Consider—the reason people can control their cars is that it’s very hard to slide a tire across pavement. Technically speaking, this is because tires are built to have a high coefficient of friction when pressed on a paved road. The coefficient of friction is essentially a ratio of the force it takes to slide two surfaces across each other to the force they’re being pressed together with. A high coefficient of friction means the two surfaces don’t like to slide; a low coefficient of friction means it’s easy. For example, let’s say you’re speeding down the highway and you see a police officer, so you step on your brakes. The amount of force it would take for your car to skid is the weight of your car (the force pressing the car to the road) multiplied by the coefficient of friction. When the pavement is dry, the coefficient of friction is high, so you can apply a lot of braking force without skidding.
On the fateful snowy day in our video, things worked a little differently. When these people pressed the brakes, the heat generated by the tire-on-ice friction created a thin film of water over the frozen surface. The coefficient of friction for tires on ice with a thin film of water between them is pretty much zip, resulting in—you guessed it—auto Ice Capades. It took almost no braking force for the cars to skid and, once skidding, they continued in a uniform motion, on a decline, until they found something that could apply enough force to stop them. The most convenient thing, as it all too often is, was another car.
There’s not a whole lot you can do in a situation like this besides try to steer out of the line of other cars and gently brake in the hopes that your antilock system helps the wheels grip again. What didn’t seem to work was when one guy jumped out of his car, grabbed the door, and tried to stop it himself. Maybe he can bench-press a few, but it’s doubtful he could have competed against the villainous combination of ice, rubber and a low coefficient of friction. —Katherine Ryder
Shortly before our crazy biker pulls the reverse-Knievel—jumping far past the landing area instead of far short—we hear one of his compatriots shout, “You can go twice as fast!” This is a faulty hypothesis, as it turns out, but to the layman it would seem to make sense. After all, our biker had previously executed a graceful flop straight into the giant pit o’ foam. Doubling the takeoff speed intuitively should double the distance he flies, putting him a little farther into the pit but still within its bounds. Right?
Not exactly. Though it’s impossible to tell from the video exactly how much faster the biker was going on the second attempt, any increase in speed would be liable to have unforeseen consequences. That’s because the best way to understand how the bike flies is not with the concept of speed, but with energy. Why? Energy, as the lab coats like to say, is always conserved—and it’s gotta go somewhere. In this case, all the energy the bike carries into the jump is used to lift the bike however many dozen feet into the air before gravity puts it back into the speed of the freefall.
The funny thing about energy, though, is that it increases with the square of speed. That means that an object going twice as fast has four times as much energy, one going three times as fast has nine times as much energy, and so on. And practically speaking, four times as much energy means our biker is going to fly four times as high and sail four times as far. Exponents, like landing distances, tend to increase quickly. It’s important to make sure your foam can accommodate them. —Michael Moyer
Far be it from us to deride anyone’s childish fascination with blowing stuff up in a microwave—a foolhardy nerd rite of passage if ever there was one—and what better place to exhibit dangerous, potentially expensive shenanigans than YouTube? The experiment is simple. Take a seedless grape and slice it lengthwise, making sure (this part is important) not to cut all the way through, so you leave a little bit of skin connecting the two halves. Put it face-up in a microwave, and blam: fireworks!
So what the heck is going on in there? Grapes are chock-full of electrolyte, an ion-rich liquid (a.k.a. “grape juice”) that conducts electricity. Each grape-half serves as a reservoir of electrolyte, connected together by a thin, weakly conducting path (the skin). Microwaves cause the stray ions in the grape to travel back and forth very quickly between the two halves. As they do this, the current dumps excess energy into the skin bridge, which heats up to a high temperature and eventually bursts into flame. At this point, the traveling electrons arc through the flame and across the gap, ionizing the air to a plasma (which itself can conduct electricity) and creating the bright flashes you see.
And that notion about poisonous gas tainting your roommate’s Hot Pocket? Well, the guy’s talking about the ozone generated when the air inside the glass is ionized. “Poisonous” might be too a strong word in this scenario (a little ozone definitely won’t kill you), although high concentrations of ozone can oxidize lung tissue and have been known to cause asthma in urban inversion-bowls like L.A. and Mexico City.
Again, DON’T TRY THIS AT HOME. Microwave ovens + biological capacitors = bad news. —Martha Harbison.
The electrons in metal are the worker ants of electricity: ubiquitous, able to work together to carry great loads, and free to roam in any direction. Since they’re unbound to any single atom or molecule, they can swim through the metal and move charge from one place to another. Air, on the other hand, lacks these mighty swimmers. All its electrons are held tight to their parent molecules. If you want to get air to conduct electricity like a metal, you have to pull those electrons away—and pull real hard.
That, in effect, is what the 500,000 volts in this switchyard are doing. When the circuit breaks at the beginning of the clip, the electrical field between the contacts is so strong that it yanks electrons free from the nitrogen and oxygen in the air. These electrons flow uninhibited between terminals as if they were in a metal and allow the air—now acting as a plasma, not a gas—to conduct electricity. It’s the same thing that happens in lightning, except lightning is one quick burst of energy from cloud to ground. Here, we’ve got a power plant spitting out energy to spare. Electricity tears the air apart so that it can flow through the cracks.
Unsurprisingly, all this activity heats the air pretty quickly. That’s why the arc—the area of lowest resistance, where the electrons can be freed from their host molecules—moves up. Hot air rises, after all. —Michael Moyer
What makes a racecar spontaneously rip a 360 backflip? A perfect storm of hills and tailgating, that’s what. In this case, driver Yannick Dalmas, racing for Team Porsche in the 1998 Petit LeMans at Road Atlanta, was drafting the car in front of him while zooming over a rise. As he crested the hill, the car’s suspension pulled up, allowing more air to flow under the car and creating lift. Simultaneously, the draft from the car in front of him interrupted the airflow over the nose of Yannick’s car, sapping the much-needed downforce that kept the car in contact with the pavement. Without that downforce, there was nothing to stop the car’s nose from continuing upward once it started. After that, it’s pure physics opera: The nose of the car leaves the draft zone and enters the airstream, which accelerates the lift and pushes the nose backward while the weight of the rear-mounted engine continues its forward momentum. Voilà! A fantastic, white-knuckled twirl that—luckily—sustained enough momentum to end upright. Must have been an awesome ride. (Dalmas walked away uninjured.) —Martha Harbison
The BBC’s clever automotive show Top Gear recently staged its own vehicular version of the Winter Olympics. The high point—pardon the pun—was when they launched a rocket-powered Mini off a ski jump. Despite the extra kick provided by the rockets, the Mini failed to match the distance of a real Olympic ski jumper. Why?
Once an object leaves the ground, we can forget about everything but four simple forces: (1) lift, which opposes (2) gravity, and (3) thrust, which opposes (4) drag. In an airplane, the engines produce enough thrust to overcome the drag created by the airframe punching a hole in the sky at hundreds of miles per hour, while the wings create enough lift to fight gravity and keep the plane aloft.
Our example is a bit simpler. A ski jumper lacks thrust, and, as we see in the video, even the Mini’s rockets are largely exhausted by the time it runs out of ramp. So we can ignore that component. Drag is important, but uninteresting, and ultimately less critical than the other two forces: lift and gravity.
Ask 100 scientists and engineers what causes lift, and most of them will probably give you some version of the nonsense the rest of us learned in school: high pressure below a wing, low pressure above. Wrong! This is a typical consequence of lift, but it’s not the cause. What creates lift, as deftly explained here by the folks who put the first “A” in NASA, is what they call “turning” the air. As air passes beneath a wing, the wing pushes that air down. By Newton’s third law (the one about every action having an equal and opposite reaction), the air must also push back up on the wing. This push is lift.
What does all this have to do with our Mini? Well, a stocky car on skis isn’t pushing air in any one direction, it’s just pushing it out of the way. That means it isn’t producing any lift. A ski jumper, on the other hand, positions her body and skis in a very precise way so as to maximize a net downward push of air. She pushes down so that the air might push back up.
But we must subtract from this push the persistent force of gravity. Fair enough. Fortunately for our jumper, the force of gravity is proportional to an object’s mass, and so the Earth pulls her down with a force less than a tenth the magnitude of the Mini’s. So our jumper’s net acceleration will be her lift (which is small but important) minus her gravity, while the Mini’s net acceleration will be its lift (which is zero) minus its gravity (which is an order of magnitude higher than the jumpers). Result: Even though the Mini might take off at a higher speed, it drops so much faster than the skier that their jump distances can’t compare. —Michael Moyer
In this clip, we watch in open-mouthed wonder as 7-foot-6-inch leviathan Yao Ming becomes the property of 5-foot-9-inch Nate Robinson. Yao, whose defender had left him to guard the ball, receives a pass and leaves his feet for what should have been an easy one-foot jumper. But Robinson flies in from the weak side, takes a strong two-footed leap, and smacks the shot out of Yao’s hands (and back into his face) just as he shoots. Yao doubles over and brings his hands to his face, covering not only his injury but his deep sense of shame.
Before analyzing the physics of this maneuver, it’s tempting to assume the following things: Robinson, who gives up 21 inches to Yao, seems to be an immeasurably more talented athlete who plays with more energy and shows more heart. He certainly has a superior vertical leap (measure the height of Robinson’s shoes relative to Yao’s leg in this clip). But Robinson is not just 21 inches shorter than Yao. At 180 pounds, he’s 130 pounds lighter than Yao’s 310. Every time Robinson jumps, he’s moving less weight, and less weight takes less energy.
Just how much less energy? Let’s figure out how Yao’s and Robinson’s vertical leaps would compare if each expended the same amount of energy. The energy of a jump—and hence the work that must go into jumping—is proportional to both the jumper’s weight and how high he gets off the ground. Since we know that Yao weighs 58.1 percent more than Robinson does (180 divided by 310 equals 0.581), we can calculate that Yao’s vertical leap should be only 58.1 percent of Robinson’s.
Although updated numbers are hard to come by, Robinson’s vertical was measured to be 42 inches when he was drafted, and Yao’s as around two feet (a note to the viewer: two-foot vertical not on display in this video). Robinson can jump twice as high as Yao, so we can conclude that Yao would have to work twice as hard to reach the same height.
The lesson: Apply the same amount of energy to a smaller body and that body will jump higher every time. That, and Yao should dunk when he’s a foot away from the basket. —Michael Moyer
Ordinarily, driving is pretty straightforward: You just point the wheels and go. But piloting an aircraft is trickier, because you not only must deal with complexities like the potential for traffic above and below the plane, but your roadway—the air—moves. Until it’s time to land, of course. Seamlessly transitioning from sky to asphalt is the most difficult thing a pilot regularly has to execute, especially when winds are strong and blowing from side to side (as in the crosswind landing featured in this video). But it’s easy enough to understand what a pilot should do in such circumstances, even if you’re too freaked out to ever in a million years attempt to do it yourself. All you need are vectors.
A vector describes how something moves; picture it as an arrow. The vector’s length describes how fast the thing is moving, and its direction tells you which way it’s going. If you threw a baseball straight up in the air, the vector that described its movement would start out long—the ball’s going fast—and pointed toward the sky. Then the vector would shorten as the ball slowed and, at the top of its arc, would flip downward and grow long again as the ball fell.
If an object is moving in or on a medium that’s also moving—a person on a moving sidewalk, a swimmer in water, a plane in the sky—you figure out how the two will move together by taking the vector for the object and the vector for the medium and joining them together head-to-tail.
In our example, the wind is whipping from left to right, so its vector points that way. For the plane to move straight ahead, its vector must cancel out the left-to-right vector of the wind. That means it has to point a little to the left, or into the wind.
Of course, once the plane hits the ground, it had better be pointing in the direction it’s moving. That’s why the pilot has to straighten the plane out at the last second. If he did it any earlier, the wind would start to pull the plane to the right; if he did it any later, the plane would hit the tarmac sideways and flip over onto its wing. And you thought parallel parking hard. —Michael Moyer
Though A-Team reruns would have you believe otherwise, vehicles that crash in real life aren’t immediately and inexorably consumed by giant explosions. Any movie geek knows this. Gasoline doesn’t explode—it burns, just like wood—except in the uncommon environment of an internal combustion engine. Yet our unlucky racer’s motorcycle blows up with such vigor, you’d think Michael Bay placed the explosive charges there himself. So what gives?
The answer lies in the way the bike tumbles across the racetrack. Take a close look at how it flips before conflagration. The first time the bike bounces off the ground, the force seems to knock the cap off the gas tank. As the bike flips again, you can see racing fuel spray out of the top of the tank in great arcs, billowing through the air along with the dirt and gravel kicked up by the skid. This, as they say, is a bad sign.
Gasoline, like every other fuel, needs oxygen to burn. Ordinarily, if you were to set a match to a pool of gasoline, only its surface would burn, because only its surface would be in contact with the oxygen in air. But as it’s injected into your engine, the gasoline is atomized (imagine a tiny gasoline spritzer set on “mist”) in order to thoroughly mix the fuel with air before your spark plug ignites the combination. Since every bit of nearby fuel is now surrounded by oxygen, this flame spreads almost instantaneously through the combustion chamber until everything is alight.
But in the case of the motorcycle explosion, the bike’s acrobatics did the work of atomizing the gasoline. Once a spark ignited the little droplets, the whole thing went up in a bang. So a word to the wise: If you’re going to have a catastrophic accident in a motorcycle race, try to keep your gas cap on. —Michael Moyer
Physics has given us a great many simple principles that make it easier to understand what’s going on in the world, some better-known than others. To wit: Every action has an equal and opposite reaction; what goes up must come down—both classics, for good reason. And the blingiest of the axioms, E=mc², is particularly useful for understanding why a fistful of plutonium can cause such a big bang. Less famous but far more important on a day-to-day basis if you’re an SUV designer, a high jumper or—as in the present case—a crane operator, is the principle that any object will behave as if all its weight is concentrated at its center of mass.
Finding an object’s center of mass is fairly simple. It’s the point at which half the mass is above the center and half below, half is on the right and half on the left, and half is in front and half in back. If you stand straight up with your arms at your sides, your center of mass is a little below your bellybutton (unless you’re J. Lo). But here’s the important part: If your center of mass is not above your feet, you’re going to fall over. The same principle works for a crane. If the center of mass of the total system—crane plus whatever it’s carrying—moves to one side of the crane’s base, the crane will tip.
As our crane lifts the bus out of the water, trouble is a-brewin’. The water itself is holding up the partially submerged bus. (Remember Archimedes? No? Here: Water pushes up on an object with a force equal to the weight of the water being displaced—this is the reason things feel lighter in water.) As the bus leaves the river, the crane takes on more of its weight until the center of mass shifts so far away from the crane’s arm that suddenly there’s a tip, a splash and the call for a bigger crane. —Michael Moyer
Everything has a beat. A rhythm. A frequency at which it likes to shake. You can rock most objects off-beat for as long and hard as you like, and not much will happen (see: the career of John Mayer). But start to push and pull in time with the natural frequency—the “resonant” frequency—of the object in question, and it will quite literally start to fall apart, much like the helicopter in the video below.
I always understood resonant frequencies best by thinking of the old-timey toy the paddleball. This uniquely solitary time-waster—Minesweeper for the Greatest Generation—consists of a bouncy red ball attached by elastic string to a small wooden paddle. Success comes when you hit the ball, the elastic pulls it back to the paddle, and you hit it again. And again and again and again. You quickly notice that there’s only one frequency that works, only one rhythm that prevents you from flailing wildly at the stupid little red ball. This is the paddle’s resonant frequency, and in this case, it’s a good thing.
Not so when dealing with bridges, skyscrapers or helicopters, however. Shake these at their resonant frequency, and the back-and-forth motion spells trouble. Each push adds more and more energy to the object—energy that, if not dissipated, starts to wreak havoc. That’s what happens with our Chinook. The rotating blades begin to shake the airframe at its resonant frequency, and physics takes care of the rest: Because the blades are unable to dissipate the excess energy, the convulsions rend them from the fuselage.
According to PopSci’s aviation expert, Bill Sweetman, helicopters are prone to resonant effects, which is why resonance ground testing (as seen in this video) is a standard part of chopper R&D. If both blades in a twin-rotor helicopter share the same heavy vibration and the engine mounts aren’t rock-solid, the energy generated can actually make the motors start moving around the engine mounts, and the next thing you know, that bird’s goose is cooked.
Sweetman also offered up this anecdotal tidbit: “Little-known fact: Charles Kaman, a U.S. heli designer who was also a bluegrass guitar player, combined his knowledge of acoustics and fiberglass (used in rotor blades) to create the Ovation guitar series.” Cue Patsy Cline’s “I Fall to Pieces”. . . —Michael Moyer
