Stories tagged Motion

Oct
16
2008

I would so not do this: Joseph Kittinger jumps out of the Excelsior III balloon at 102,800 feet.
I would so not do this: Joseph Kittinger jumps out of the Excelsior III balloon at 102,800 feet.Courtesy US Air Force
I attended yet another great Cafe Scientifique event put on by the Bell Museum the other night called: Art and Aeronautics—A Conversation with Tomás Saraceno. Tomás and his teammate Alberto are artists in residence at the Walker Art Center in Minneapolis and have been working with the Aerospace Engineering and Mechanics department at the University of Minnesota. In short they are building a giant balloon out of reclaimed trash--primarily plastic bags. This talk got me on an balloon science research kick and thought I would share some links:
First off, check out some of the pics of Tomás and Alberto's project, the Museo Aero Solar.

There was lots of talk at the presentation about women's important role in the early days of flight when ballooning dominated. There was even some debate about whether a woman was the first person in space...via balloon...in the 1920s! I couldn't immediately find any information on this claim on ye old internets, but I would love to hear from any buzz readers who might know more information.

Getting to space by balloon might seem crazy, but that's exactly what the Air Force was trying to do before our attempts with rockets. Check out Project Manhigh(yep its really called that) and Project Excelsior. Several of these early space balloons were piloted by Air Force Colonel Joseph Kittinger, the first, possibly only, man to ever break the speed of sound, without a vehicle. He did it by jumping out of a balloon about 20 miles up.

Students are getting into the high altitude balloon game all over the place as well: reusable experiment platform goes to the edge of space, pics at the edge of space, and legos in space.

I think balloons are my new favorite science obsession.

Oct
15
2008

I have thought about designing a car that would run off a small windmill behind the grill. It would spin the alternator which would run the car and recharge the batteries. It would allow anyone to drive forever without using any gas. If the car looked like any other car, would you buy it, especially if it cost the same as a "regular car"?

Oct
15
2008

Is it possible to calculate the "potential energy" of a particular Offensive line compared to a particular Defensive line?

Should a Coach know if they are statistically unable to force the line of scrimmage the direction they want?

Sure - weaknesses can be exploited by double teaming, and running slant plays.....checking the stats on each lineman the coach should be able to choose their strategy before the game....and give the best chance of success

Oct
01
2008

Yer outta here!: Physics play a big role in the National Pastime.
Yer outta here!: Physics play a big role in the National Pastime.Courtesy Mark Ryan
With the baseball play-offs and World Series coming up, I’m sure lots of folks out there (especially in Chicago and not so much in Minnesota) are agonizing over the question: What is more effective, sliding into base head-first or feet-first?

Well, as usual, science has solved the problem. Using physics and mathematics, David A. Peters, an engineer from Washington University in St. Louis, has figured out which of the two ways is more advantageous. Peters is a huge baseball fan, and a mechanical engineer to boot. He explains it this way:

"There's momentum— mass of the body times how fast the player is moving. There's angular momentum (mass movement of inertia times the rotational rate). If it's feet-first and you're starting to slide, your feet are going out from you and you're rotating clockwise; if it's head-first, as your hands go down, you're rotating counterclockwise. On top of this is Newton's Law: Force is mass times acceleration. Then moments of inertia times your angular acceleration."

So which method gives ballplayers a better chance of making it safely to the bag? Center of gravity seems to be the key.

"It turns out your center of gravity is where the momentum is. This is found half way from the tips of your fingers to the tips of your toes. In the headfirst slide, the center of gravity is lower than halfway between your feet and hands, so your feet don't get there as fast. It's faster head-first."

Regardless of the science, Dr. Peters figures preference for one way or the other among ballplayers is about 50/50. And the whole argument goes out the window when talking about first base. Usually, players are much better off running through first rather than sliding into it at all.

"Mathematically, you might think there's an advantage, but leaving your feet is actually a detriment because you're no longer pulsing (pumping your legs) and you start to decelerate," he says. "When you're running, your get your feet out in front of the center of gravity, so you're getting maybe three or four steps of an advantage."

Dr. Peters was also involved in a previous baseball study covered by the Buzz back in July.

SOURCE
Washington University story

Sep
27
2008

Fluid flow separation: The fluid flow becomes detached from the surface of the object, and instead takes the forms of eddies and vortices.
Fluid flow separation: The fluid flow becomes detached from the surface of the object, and instead takes the forms of eddies and vortices.Courtesy jaganath

Fluid flow separation explained with mathematics in 1904

In 1904, Ludwig Prandtl, considered the father of modern aerodynamics, derived the exact mathematical conditions for flow separation to occur, but only in two dimensions for steady flows.

Unsteady fluid flow in three dimensions explained with mathematics in 2008

A century later, George Haller, a visiting professor in the Department of Mechanical Engineering at MIT led a group that explained the mathematics behind unsteady separation in two dimensions. This month, his team reports completing the theory by extending it to three dimensions. Papers on the experiments and theory are being published in the Sept. 25 issue of the Journal of Fluid Mechanics and in the September issue of Physics of Fluids, respectively. Haller's coauthors are Amit Surana, now at United Technologies; MIT student Oliver Grunberg; and Gustaaf Jacobs, now on the faculty at San Diego State University.

Fluid mechanics theorists are excited

The equation will forever change the face of advanced fluid dynamics and will have a profound impact on many industries, including the aerospace and automotive industries. This quote from Daily Tech Review shows that this breakthough has theorists in fluid mechanics excited;

The new work -- if it survives the extensive peer review that is to come -- will likely go down as the greatest scientific advance of the decade. The research has already survived a strenuous initial round of peer review.

Equally important, this month Thomas Peacock, the Atlantic Richfield Career Development Associate Professor and his colleagues report important experimental work verifying the theory.

"This is the tip of the iceberg, but we've shown that this theory works," Peacock said.

Fluid dynamics makes a difference

Understanding how surfaces effect how an object flows through a fluid (including air) can make big differences in maximizing performance. Did the new swimsuits make a difference in breaking world records in Olympic swimming competition? How about the surfaces of baseballs, golf balls, and tennis balls? The effects on miles per gallon for autos and airplanes can save millions (billions?) of dollars.

Source: MIT News

Aug
19
2008

A motorcycle race...: In the future!
A motorcycle race...: In the future!Courtesy Private Custard
A student in the transportation program of the < a href=http://www.artcenter.edu/>Art Center College of Design has invented a brand new paradox: a concept-motorcycle that is somehow simultaneously totally awesome and utterly, hopelessly dorky.

It’s a mega future tri-moto electro cyber transporto THX laser blade runner terminatrix rideable machine.

I guess they call it the conceptual exoskeleton motorcycle, Deus Ex Machina. But I think my name for it is still less dorky.

What? You want an actual description of the vehicle? Well, you could just click on the long link above, and leave Science Buzz forever, but we like you here. So at least read the rest of the post before you go.

The Deus Ex Machina is sort of a wheeled tripod, with straps and an integrated helmet to secure the rider. It parks in an upright position, but once it starts moving, the “arms” of the tripod extend forward, so the rider is in a sort of superman position. The motorcycle steers according to the rider’s body position, translating movement to 36 pneumatic muscles. Like, um, Robocop, I think.

The whole vehicle is powered with electricity, using fancy lithium ion batteries and ultracapacitors (check out ARTiFactor’s post for more on ultracapacitors), and is capable of reaching speeds of around 75 mph.

The Ultra Deus Mega Electromachina motorcycle is still very much conceptual, however. That is to say, while all the technological components exist (in some form) the vehicle itself only exists as a computer rendering at the moment. So it’s probably not very fun to ride. The designer maintains that it’s not a fantasy: “It’s a green vehicle,” he says, “and all of the numbers are based in the real world.”

The design itself seems more based in the Minority Report world, but whatev.

There’s a video here, too.

Feb
03
2008

It's very pretty: Perhaps the new invention is for performance art.
It's very pretty: Perhaps the new invention is for performance art.Courtesy US Navy
On the last day of January, the United States Navy tested a strange and remarkable new machine, the purpose of which remains unclear to the writer.

The powerful new machine uses electromagnetic energy to hurl an object (something pointy and metal, it looks like) over 230 miles. The flying object can obtain airspeed seven times the speed of sound.

A demonstration of the device can be seen in thisvideo released with the story. It seems the machine was inadvertently aimed at a solid wall during the demo. The wall, lamentably, was demolished by the sheer kinetic energy of the flying object. Despite this embarrassing mishap, the navy seems very pleased with the invention, and hopes to have a “full-capability prototype” working within the next ten years.

Any ideas what this thing-launcher could possibly be used for? It looks like it could be awfully dangerous, should someone find themselves in the path of a launched thing – whatever they want it for, the Navy will have to be very careful with the new device.

Dec
15
2007

Window washers: Remember, guys: belly down.
Window washers: Remember, guys: belly down.Courtesy Poagao
On the subject of falling from great heights (and surviving), the New York Times reported a couple days ago on a man who fell 47 floors from a New York apartment building and lived.

The man and his brother were washing the windows of the building when their platform gave way and plummeted into the Manhattan air. When emergency services arrived, one of the men was dead, but the other was already sitting up and conscious (though seriously injured). Authorities are still uncertain as to how he could have survived.

Their best guess, however, is that the man followed his training for such a situation. In the event of a high scaffolding collapse, apparently, one is supposed to flatten his or her body against the platform, belly down. The idea is that the greater surface area of the material should generate some small wind-resistance, slowing the fall. The lightweight material of the platform may also absorb some of the shock upon landing. The main thing is to be lucky, though.

Anyway, they think that the surviving man probably did something like this, and that his brother either did not have the chance to do so, or panicked, and leapt from the falling platform (which, I guess, is what instinct dictates).

The article briefly mentions two other similarly baffling fall-and-survive stories; an amateur sky-diver whose parachute failed to open, and fell from a mile up into a three-foot-deep duck pond, as well as the slightly less amazing - but closer to home - story of a drunk man falling seventeen stories in a Minneapolis hotel atrium (Twin Cities represent! Our drunks fall way better than anyone else’s!)

For a fun and slightly less horrifying lesson in density, gravity, and acceleration, come check out the SMM’s Science Live “Free Fall” show, where we drop stuff from the top of our own fifty-foot atrium (usually water balloons instead of drunks, though).

Dec
13
2007

A swarm of humans: The sky is full of human gliders in the flying-squirrel-like outfits. The winged suits are the newest trend in sky diving, giving jumpers the chance to glide at up to speeds of 140 miles per hour.
A swarm of humans: The sky is full of human gliders in the flying-squirrel-like outfits. The winged suits are the newest trend in sky diving, giving jumpers the chance to glide at up to speeds of 140 miles per hour.Courtesy Matt Hoover
Working on the museum floor the other day, one of the volunteers in my gallery was telling me all about human gliding. He’s big on aviation and had some interesting stuff to share on things he’s heard about and seen (but not actually done).

Unfortunately, I wasn’t able to take any notes at the time, but it got me curious enough to Google around and learn more about human gliding. It appears to be just the thing for the sky-diving veteran who’s looking for a bigger adrenaline buzz.

How does this work?

The wingsuit that human gliders wear essentially turns them into a parachute. The flaps between the wearer’s limbs create an airfoil that generates lift as they inflate with air. Gliders can then manipulate their bodies to control the direction and speed of their descent. Jumping from a moving aircraft like an airplane or helicopter also gives the human glider forward speed that translates into lift potential which slows down the fall rate of gliders and gives them a higher glide ratio.

Here’s an awesome YouTube video of a human glider in action. (Warning: The video itself is unobjectionable, but the comments posted to YouTube contain profanity and other strong language.)

Human gliders, when keeping their bodies parallel to the horizon, can reach speeds of 110 to 140 miles per hour. Many human gliders, however, find it a bigger challenge to see how slow they can glide while maintaining their aerodynamics, sort of, but not completely like, stunt pilots stalling out their engines when they’re doing tricks. Some human gliders have slowed themselves down to speeds as low as 25 miles per hour and have lived to talk about it. A more conventional slow speed, however, is about 60 miles per hour.

A closer look: From above, here's a closer view of what's involved with human gliding.
A closer look: From above, here's a closer view of what's involved with human gliding.Courtesy Matt Hoover
While it’s still a pretty new technology to be used in the sky diving realm with experiments going back about 10 or 15 years, man has been striving to glide through the air for ages.

In the modern era, between 1930 and 1961 there were 71 reported deaths of people attempting to glide or fly with wings attached to their bodies. There were also four successful flights in that same time.

And it appears that human gliding advancements aren’t going to hit the wall any time soon. Experiments are now underway in attaching jet burners to the shoes of human gliders, giving them more thrust and speed to play around with in the skies.

It should go without saying, but nevertheless, don’t try this at home kids, Jackass actors or any others who are easily tempted to display poor judgment. Human gliders are very experienced skydivers who have studied up on this type of aerodynamics.

That all said, is this something that you’d want to try? Share your thoughts here with other Science Buzz readers.

Here are some links if you’d like to learn more about human gliding.

Technovelgy.com

Lucky Aviation

Wikipedia