Sleepysneezeydopeydoc-blog - Physics Nerd

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Mathematical Spirals

According to Wikipedia, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point (similar to helices [plural for helix!] which are three-dimensional). Pictured above are some of the most important spirals of mathematics.

Logarithmic Spiral: Equation: r=ae^bθ. I must admit that these are my favorite! Logarithmic spirals are self-similar, basically meaning that the spiral maintains the same shape even as it grows. There are many examples of approximate logarithmic spirals in nature: the spiral arms of galaxies, the shape of nautilus shells, the approach of an insect to a light source, and more. Additionally, the awesome Mandelbrot set features some logarithmic spirals. Fun fact: the Fibonacci spiral is an approximation of the Golden spiral which is only a special case of the Logarithmic spiral. 

Fermat’s Spiral: Equation: r= ±θ^(½). This is a type of Archimedean spiral and is also known as the parabolic spiral. Fermat’s spiral plays a role in disk phyllotaxis (the arrangement of leaves in a plant system). 

Archimedean Spiral: Equation: r=a+bθ. The Archimedean spiral has the property that the distance between each successive turning of the spiral remains constant. This kind of spiral can have two arms (like in the Fermat’s spiral image), but pictured above is the one-armed version. 

Hyperbolic Spiral: Equation: r=a/θ. It is also know as the reciprocal spiral and is the opposite of an Archimedian spiral. It begins at an infinite distance from the pole in the center (for θ starting from zero r = a/θ starts from infinity), and it winds faster and faster around as it approaches the pole; the distance from any point to the pole, following the curve, is infinite. 

BeerBellyBlunt

If you put that ball on that machine while it wasn’t spinning, it would just roll straight down the lower sides. 

The raised edges would keep it in the middle line, but it’s only controlled in one direction. By spinning it, you constantly alternate the position of the tall sides, meaning that the ball is held in the middle, never able to fall off.

Particle accelerators control particles in the same way. Magnetic or electric fields can only direct particles in one plane at a time, so to keep a beam of particles rushing down a particle accelerator in one focused stream, the current gradient must constantly oscillate. This means the particles are constantly held in place, never able to shoot off in one direction.

Here’s the same principle in action: these are tiny pollen grains being held in place by an oscillating field. Rods in the four corners of the beam establish a field that oscillates many times a second to keep the pollen trapped. If it didn’t constantly switch, the pollen would all fly off in one direction.

Watch the full film with Dr Suzie Sheehy for more.

Physical Science...In Space!

Each month, we highlight a different research topic on the International Space Station. In May, our focus is physical science.

The space station is a laboratory unlike any on Earth; on-board, we can control gravity as a variable and even remove it entirely from the equation. Removing gravity reveals fundamental aspects of physics hidden by force-dependent phenomena such as buoyancy-driven convection and sedimentation.

Gravity often masks or distorts subtle forces such as surface tension and diffusion; on space station, these forces have been harnessed for a wide variety of physical science applications (combustion, fluids, colloids, surface wetting, boiling, convection, materials processing, etc).

Other examples of observations in space include boiling in which bubbles do not rise, colloidal systems containing crystalline structures unlike any seen on Earth and spherical flames burning around fuel droplets. Also observed was a uniform dispersion of tin particles in a liquid melt, instead of rising to the top as would happen in Earth’s gravity. 

So what? By understanding the fundamentals of combustion and surface tension, we may make more efficient combustion engines; better portable medical diagnostics; stronger, lighter alloys; medicines with longer shelf-life, and buildings that are more resistant to earthquakes.

Findings from physical science research on station may improve the understanding of material properties. This information could potentially revolutionize development of new and improved products for use in everything from automobiles to airplanes to spacecraft.

For more information on space station research, follow @ISS_Research on Twitter!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

The best vintage cars, hot rods, and kustoms

Dudeney dissection from a square to an equilateral triangle. Only 4 pieces!

New organic lasers one step closer to reality

New research could make lasers emitting a wide range of colors more accessible and open new applications from communications and sensing to displays.

Researchers at Kyushu University’s Center for Organic Photonics and Electronics Research (OPERA) reported an optically pumped organic thin-film laser that can continuously emit light for 30 ms, which is more than 100 times longer than previous devices.

Unlike the inorganic lasers commonly found in CD drives and laser pointers, organic thin-film lasers use a thin layer of organic molecules as the laser medium, which is the material in the device that actually produces lasing by emitting and amplifying light when excited with an energy source. In this case, the energy source was intense ultraviolet light from an inorganic laser.

A very promising feature of organic thin-film lasers is the possibility to more easily achieve colors that are difficult with inorganic lasers. By designing and synthesizing molecules with new structures, emission of any color of the rainbow is possible.

Read more.

Alloys: Bronze

Given that there are many different types of bronze with a wide variety of elements included, the alloy cannot be defined as having one set composition. Though the most well known bronze is likely the common copper-tin alloy, alloys such as bismuth bronze, silicon bronze, and aluminum bronze don’t necessarily contain tin.

That being said, the most well known bronze alloy, and the one most people probably think of when they hear the word, is composed of mostly copper with tin or arsenic and, potentially, small amounts of other elements. The oldest tin-copper bronze alloys found are from around 4500 B.C., and this replacement of stone tools with bronze eventually led to the Bronze Age. (The Bronze Age eventually gave way to the Iron Age, because, despite bronze’s favorable properties, iron is more plentiful and easier to find.)

The addition of tin, arsenic, and other elements produces a harder material than copper alone. Bronze also has the favorable properties of being corrosion resistant, non-magnetic, has excellent heat transfer properties, is relatively easy to machine, withstands high temperatures, and is resistant to wear and friction. Unlike steel, bronze does not spark when struck and is therefore useful as tools in environments containing flammable vapors. 

Some historical applications of bronze include in statues, weapons and tools, and currency/coinage. The alloys is also well known for is usage in musical instruments, often bells and cymbals, as well as the windings of string instruments such as the guitar and piano. 

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Image sources: ( 1 ) ( 2 ) ( 3 )

God damn it Isaac! 😡😡