More Than You Ever Wanted To Know About Mechanical Engineering, Part 33: Stress Concentrations With Fluctuating

coolest physics thing that u know??

The coolest physics thing that I know keeps changing over time. But here is one that is extremely fascinating ( and also exaggerated for the effect ; but true! ):

Person living at the top of a skyscraper experiences time faster than one at the bottom

It is a known fact that the higher you are in the earth’s ** atmosphere, the lesser the effect of gravity is.

But the lesser the effect of gravity is, the faster the time ticks.

By how much you ask? Even if you live on the top floor of the Burj Khalifa  your entire life, you would have aged more only by a few milliseconds than your friends at the bottom. 

( Sure, doesn’t seem like much, but hell would break loose if we don’t consider this on the bigger scale of things )

This is known as Gravitational time dilation and is at the foundations of General Theory of Relativity. (More about this in an upcoming post)

Have a great day and thanks for asking!

EDIT: ** Lets just say hypothetically the earth is not spinning( just to ignore special relativistic effects) and we are looking at only the effects of height.

Ceramics: Aluminum Nitride

First synthesized in the late 1800s, aluminum nitride’s potential wasn’t realized until a hundred years later in the late 1900s. AlN is a ceramic with high thermal conductivity but is an electrical insulator. It is classified as a covalent compound, the only stable compound in the binary Al-N system. 

AlN is similar in properties to beryllium oxide (BeO), but is cheaper and has less of a potential to be toxic. In addition to the properties mentioned above, this ceramic also has high chemical resistance and exhibits piezoelectric properties. 

Thanks to its thermal and electrical conductivity properties, AlN is useful in microelectronics. It is used in microelectronic packaging, surface acoustic wave sensors, in RF filters, as a crucible for the growth of gallium arsenide crystals, in piezoelectric MEMs applications, and many more. In addition, the wurtzite phase of aluminum nitride, w-AlN, is a wide band gap semiconductor material, with potential applications in deep ultraviolet optoelectronics. 

Because AlN is a covalent compound, high pressures or sintering aids are required to assist densification during production. Typical additives include rare-earth or alkaline-earth oxides, such as yttrium compounds. The additives and sintering conditions used can alter the properties of commercially available grades of AlN.

Sources: ( 1 ) ( 2 - images 2 and 3 ) ( 3 - images 1 and 4 ) ( 4 )

Does one of these LEGO men look bigger than the other? They’re actually the exact same size, but are in an Ames room - a false-perspective illusion room that tricks your brain into thinking things are smaller, or larger, than they really are.

You can make one of these models to try this for yourself. Download our free template from here. And it even works in full size, if you can make one large enough!

Chances of hypersonic travel heat up with new materials discovery

Researchers at The University of Manchester in collaboration with Central South University (CSU), China, have created a new kind of ceramic coating that could revolutionise hypersonic travel for air, space and defense purposes.

Hypersonic travel means moving at Mach five or above, which is at least five times faster than the speed of sound. When moving at such velocity the heat generated by air and gas in the atmosphere is extremely hot and can have a serious impact on an aircraft or projectile’s structural integrity. That is because he temperatures hitting the aircraft can reach anywhere from 2,000 to 3,000 °C.

The structural problems are primarily caused by processes called oxidation and ablation. This is the when extremely hot air and gas remove surface layers from the metallic materials of the aircraft or object travelling at such high speeds. To combat the problem materials called ultra-high temperature ceramics (UHTCs) are needed in aero-engines and hypersonic vehicles such as rockets, re-entry spacecraft and defence projectiles.

But, at present, even conventional UHTCs can’t currently satisfy the associated ablation requirements of travelling at such extreme speeds and temperatures. However, the researchers at The University of Manchester’s and the Royce Institute, in collaboration with the Central South University of China, have designed and fabricated a new carbide coating that is vastly superior in resisting temperatures up to 3,000 °C, when compared to existing UHTCs.

apparently one whale years ago was observed doing this for hours and now more and more whales in the area are seen copying it so we think it’s a whole new behavior and it seems to be a response to shrinking food sources.

Instead of expending any energy actively hunting, the whale just holds its mouth open wherever fish are being hunted by birds. To escape the birds, the fish try to hide in the whale’s mouth because it’s a darker area that looks like shelter. …They’re turning into giant, sea-mammal pitcher plants.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.12557?referrer_access_token=bXLTS5BeSw_vlIKHkM0bYIta6bR2k8jH0KrdpFOxC654HjreJ8D19K86UreR5JPsSRb0CuGhiJSV1L1ht-N1Gf_K_1a9MREFzQGU9oJDNctsKDin_HXcYEdsLg3EbcTl

Møbius donut.

18 Science Facts We Didn't Know at The Start of 2017

We've learned so much already.

1. Lungs don’t just facilitate respiration - they also make blood. Mammalian lungs produce more than 10 million platelets (tiny blood cells) per hour, which equates to the majority of platelets circulating the body.

2. It is mathematically possible to build an actual time machine - what’s holding us back is finding materials that can physically bend the fabric of space-time.

3. Siberia has a colossal crater called the ‘doorway to the underworld’, and its permafrost is melting so fast, ancient forests are being exposed for the first time in 200,000 years.

4. The world’s first semi-synthetic organisms are living among us - scientists have given rise to new lifeforms using an expanded, six-letter genetic code.

5. Vantablack - the blackest material known to science - now comes in a handy ‘spray-on’ form and it’s the weirdest thing we’ve seen so far this year.

6. It’s official: time crystals are a new state of matter, and we now have an actual blueprint to create these “impossible” objects at will.

7. A brand new human organ has been classified, and it’s been hiding in plain sight this whole time. Everyone, meet your mesentery.

8. Carl Sagan was freakishly good at predicting the future - his disturbingly accurate description of a world where pseudoscience and scientific illiteracy reigns gave us all moment for pause.

9. A single giant neuron that wraps around the entire circumference of a mouse’s brain has been identified, and it appears to be linked to mammalian consciousness.

10. The world’s rarest and most ancient dog isn’t extinct after all - in fact, the outrageously handsome New Guinea highland wild dog appears to be thriving.

11. Your appendix might not be the useless evolutionary byproduct after all. Unlike your wisdom teeth, your appendix might actually be serving an important biological function - and one that our species isn’t ready to give up just yet.

12. After 130 years, we might have to completely redraw the dinosaur family tree, thanks to a previously unimportant cat-sized fossil from Scotland.

13. Polycystic ovary syndrome might actually start in the brain, not the ovaries.

14. Earth appears to have a whole new continent called Zealandia, which would wreak havoc on all those textbooks and atlases we’ve got lying around.

15. Humans have had a bigger impact on Earth’s geology than the infamous Great Oxidation Event 2.3 billion years ago, and now scientists are calling for a new geological epoch - the Anthropocene - to be officially recognised.

16. Turns out, narwhals - the precious unicorns of the sea - use their horns for hunting. But not how you’d think.

17. Human activity has literally changed the space surrounding our planet - decades of Very Low Frequency (VLF) radio communications have accidentally formed a protective, human-made bubble around Earth.

18. Farmers routinely feed red Skittles to their cattle, because it’s a cheap alternative to corn. ¯\_(ツ)_/¯

If you trace the orbits of Earth and Venus over 8 years, this is the pattern that emerges

That Time We Flew Past Pluto…

Two years ago today (July 14), our New Horizons spacecraft made its closest flyby of Pluto…collecting images and science that revealed a geologically complex world. Data from this mission are helping us understand worlds at the edge of our solar system.

The spacecraft is now venturing deeper into the distant, mysterious Kuiper Belt…a relic of solar system formation…to reach its next target. On New Year’s Day 2019, New Horizons will zoom past a Kuiper Belt object known as 2014 MU69.

The Kuiper Belt is a disc-shaped region of icy bodies – including dwarf planets such as Pluto – and comets beyond the orbit of Neptune. It extends from about 30 to 55 Astronomical Units (an AU is the distance from the sun to Earth) and is probably populated with hundreds of thousands of icy bodies larger than 62 miles across, and an estimated trillion or more comets.

Nearly a billion miles beyond Pluto, you may be asking how the spacecraft will function for the 2014 MU69 flyby. Well, New Horizons was originally designed to fly far beyond the Pluto system and explore deeper into the Kuiper Belt. 

The spacecraft carries extra hydrazine fuel for the flyby; its communications system is designed to work from beyond Pluto; its power system is designed to operate for many more years; and its scientific instruments were designed to operate in light levels much lower than it will experience during the 2014 MU69 flyby.

What have we learned about Pluto since its historic flyby in 2015?

During its encounter, the New Horizons spacecraft collected more than 1,200 images of Pluto and tens of gigabits of data. The intensive downlinking of information took about a year to return to Earth! Here are a few things we’ve discovered:

Pluto Has a Heart

This image captured by New Horizons around 16 hours before its closest approach shows Pluto’s “heart.” This stunning image of one of its most dominant features shows us that the heart’s diameter is about the same distance as from Denver to Chicago. This image also showed us that Pluto is a complex world with incredible geological diversity.

Icy Plains

Pluto’s vast icy plain, informally called Sputnik Planitia, resembles frozen mud cracks on Earth. It has a broken surface of irregularly-shaped segments, bordered by what appear to be shallow troughs.

Majestic Mountains

Images from the spacecraft display chaotically jumbled mountains that only add to the complexity of Pluto’s geography. The rugged, icy mountains are as tall as 11,000 feet high.

Color Variations

This high-resolution enhanced color view of Pluto combines blue, red and infrared images taken by the New Horizons spacecraft. The surface of tPluto has a remarkable range of subtle color variations. Many landforms have their own distinct colors, telling a complex geological and climatological story.

Foggy Haze and Blue Atmosphere

Images returned from the New Horizons spacecraft have also revealed that Pluto’s global atmospheric haze has many more layers than scientists realized. The haze even creates a twilight effect that softly illuminates nightside terrain near sunset, which makes them visible to the cameras aboard the spacecraft.

Water Ice

New Horizons detected numerous small, exposed regions of water ice on Pluto. Scientists are eager to understand why water appears exactly where it does, and not in other places.

Stay updated on New Horizons findings by visiting the New Horizons page. You can also keep track of Pluto News on Twitter via @NASANewHorizons.

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