Tag: gas

Science Tackles The Hard Questions At Last: How To Create A Perfect Bubble

Blowing soap bubbles is child’s play, but surprisingly, physicists haven’t worked out the details of the phenomenon.

Now researchers have performed experiments and developed a complete theory of the process of soap bubble formation.

The team aimed a jet of gas at a soap film and observed that bubbles appear only above a threshold gas speed.

By measuring this threshold under varying conditions, the team showed that bubbles result from a competition between the pressure of the gas jet and the surface tension of the soap film.

Understanding the physics of bubbles is important for a variety of industrial processes and scientific fields, from cosmology to foam science, and the new experiments may also be useful in the classroom.

Researchers have studied related processes, such as the popping of bubbles, and examined soap films being pierced by pellets or liquid droplets.

But bubble blowing has mostly been overlooked, say Laurent Courbin and Pascal Panizza, both of the French National Centre for Scientific Research (CNRS) and the University of Rennes 1.

While watching children blowing bubbles in a local park, they realized that the phenomenon hadn’t been studied before and hurried back to the lab to tinker with soapsuds.

Following the example of previous soap film research on fluid flows and turbulence, Courbin, Panizza, and their colleagues built a large apparatus capable of creating a meter-tall, long-lived, vertical sheet of soap solution.

In this system, the soap film continually flows downward—unlike the stationary film in a standard bubble wand—and the liquid is collected at the bottom and pumped back to the top.

This laboratory setup allows the film to remain stable indefinitely, and its thickness can be adjusted, as can the speed with which it falls.

The team placed a gas nozzle at the surface of the soap film and used a high-speed camera to capture the results. At low gas jet speeds, only a small dimple appeared in the soap film.

The dimple became deeper as the team increased the jet’s speed, until bubbles finally formed.

The phenomenon, the researchers found, can be explained as a contest between the pressure the gas jet exerts on the film and the surface tension of the film, which resists any increase in curvature.

Bubbles form when the jet’s pressure is large enough to deform the film into a hemispheric dimple of the same width as the jet.

At that point, the film has reached its maximum curvature, and the bubble can fill with gas and float away.

The researchers found that wider jets, which produce larger bubbles, create them at lower gas speeds than narrower jets. These larger bubbles have less curvature, making it easier to overcome surface tension’s pull.

Repeating the study with a simple bubble wand gave similar results, suggesting that the laboratory setup is a passable proxy for real-world bubble blowing.

The thickness of the soap film had no effect on the gas speed at which bubbles formed.

Understanding how bubbles form is important for certain industrial processes, like those involving foam production, and avoiding bubble formation is necessary in glassmaking and coating solids with liquids, says Courbin.

But “this paper is really about explaining an everyday-life experiment,” rather than real-world applications, he says.

Still, says Hamid Kellay of the University of Bordeaux in France, “it’s the first time that these types of ideas can be tested correctly, because of the well-controlled experiments.

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Pass it on: Popular Science

Simple Tricks For Better Gas Mileage

No matter what kind of car you drive, you can be getting better fuel economy than what you’re getting now. Did you know you can get better mileage by never filling up your tank?

It’s true, and most of these tips and tricks will extend the range for any car ever made, even if it’s electric. Some of them are effortless, and some require dedication, but they’ll all work.

Ditch the MPG ratings

Numbers can be manipulated any which way you want, but the simple truth is that MPG doesn’t really tell you how much money you’re spending on fuel.

G/100miles, on the other hand, will. How do you figure it out? Just type in your MPG in Google as “XX MPG per 100 miles,” and multiply your answer by whatever you pay for fuel in your area. Bam.

Now you know how much or little the following tips will help you, so you can see if it’s worth it.

Lay off the damn loud pedal

You’ve heard this one before about a million times, and you know what? It’s still true.

Every time I see some moron in a Prius out accelerate me off a light I wish I had the legal right to pull him or her over, pry their eyes open Clockwork Orange-style and force them to watch Jeremy Clarkson getting better fuel economy in a BMW M3 than the Stig in a Prius.

Even the worst fuel-sipping cars made will become gas guzzlers when you floor it. More acceleration requires more energy. Guess where your car gets its energy from.

And the brake

Obviously you’ll have to stop at some point, but if you know you’re turning soon or there’s a sharp bend in the road, coast for a bit.

There are two reasons for this. 1) all your brakes do is convert your forward momentum into heat energy, and even the best energy recovery systems don’t capture 90% of that energy.

2) if you don’t slow down for a turn you have to take it faster, which is not only fun, it means you don’t have to accelerate as much.

Last year, I compared hypermiling in a hybrid to some seriously fun driving. After 100 miles, the difference was one freaking dollar’s worth of fuel.

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New Telescope In Chile Unveils Stunning First Images

The first released VST image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This vast region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer)

A new state-of-the-art telescope has snapped its first impressive images of the southern sky over the Paranal Observatory in Chile.

The VLT Survey Telescope (VST) is the latest addition to the European Southern Observatory’s network of telescopes at Paranal in the Atacama Desert of northern Chile.

The first image released from the VST shows the spectacular star-forming region Messier 17, also known as the Omega nebula or the Swan nebula, as it has never been seen before.

This nebula, full of gas, dust and hot young stars, lies in the heart of our Milky Way galaxy, in the constellation of Sagittarius.

The VST’s field of view is so large that is able to observe the entire nebula, including its fainter outer parts.

The second of the newly released images is a portrait of the star cluster Omega Centauri in unprecedented detail. Omega Centauri is the largest globular cluster in the sky and the VST’s view includes about 300,000 stars.

ESO’s new telescope

The VST is a 2.6-meter telescope with a 268-megapixel camera, called OmegaCAM, at its core. The visible-light telescope is designed to map the sky both quickly and with precise image quality.

The VST is a wide-field survey telescope with a field of view twice as broad as the full moon. It is the largest telescope in the world designed to exclusively survey the sky in visible light.

ESO officials oversee many telescopes based at three observing sites in Chile’s high Atacama Desert. In addition to the telescopes atop the summit of Cerro Paranal, the observatory has sites at La Silla and Chajnantor.

Mapping the cosmos

Over the next five years, the VST and its OmegaCAM will make three detailed surveys of the southern sky, and the data will be made public for astronomers around the world to analyze.

The KIDS survey will image several regions of the sky away from the Milky Way. The study aims to further astronomers’ understanding of dark matter, dark energy and galaxy evolution, and find many new galaxy clusters.

The VST ATLAS survey will cover a larger area of sky and focus on understanding dark energy and supporting more detailed studies using the VLT and other telescopes.

The third survey, VPHAS+, will image the central plane of the Milky Way to map the structure of the galactic disc and its star formation history.

VPHAS+ will yield a catalogue of around 500 million objects and is expected to discover many new examples of unusual stars at all stages of their evolution.

The VST project is a joint venture between ESO and the National Institute for Astrophysics (INAF) in Naples, Italy.

The Secret Blue Ice Cloud In Every Champagne Bottle

Like ice cream and revenge, champagne is best served cold, ideally between 42.8 and 53.6 degrees Fahrenheit.

But if you’re forced to drink it at 68 degrees Fahrenheit, just below room temperature, something fleeting but amazing will happen.

Scientists at the University of Reims, in France’s Champagne region, used a super-high-speed camera to observe a short-lived, blue “mini-cloud” escaping the tepid bottle—a cloud that hangs around for just two to three thousandths of a second.

That plume of cyan gas is colder than ice, and blue as the circumstances (lukewarm champagne). Researchers published their work in the journal Scientific Reports earlier this week.

This cloud was “totally unexpected,” coauthor Gerard Liger-Belair, an expert in bubbles and foam said.

Most people who have popped a bottle of cold champagne will be familiar with the wisps of white fog that cascade from the bottleneck. Before it’s been opened, champagne is under high pressure, hence the cage on the cork.

But when it’s open and the pressure adjusts, carbon dioxide pours forth. At 68 degrees Fahrenheit, however, that white mist is very briefly replaced with blue.

If the color of the blue reminds you of the sky, there’s a reason for that. The sky gets its shade from molecules scattering blue light from the sun.

The bluish cloud forms when the CO2 transforms into miniature particles of dry ice which reflect the ambient light,” Liger-Belair said.

This blue cloud has the same physical origin as the blue color of the sky. Is that not extraordinary?

It is indeed extraordinary, but perhaps not wondrous enough to justify drinking your champagne at 68 degrees Fahrenheit—especially since you’re not going to see magic blue cloud without high-speed imaging.

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Pass it on: Popular Science