IMPOSSIBLE! Right? You May Have Heard “the Interior Angles Of A Triangle Always Add Up To 180 Degrees”.

IMPOSSIBLE! Right? You May Have Heard “the Interior Angles Of A Triangle Always Add Up To 180 Degrees”.

IMPOSSIBLE! Right? You may have heard “the interior angles of a triangle always add up to 180 degrees”. This is not always true. Check out the second image, it shows a triangle with 3 right angles for a total of 270 degrees! 

It is true in flat Euclidean geometry (the geometry you probably learned in school) however. But there are so many other geometries out there! You may be thinking, are other geometries real though? A mathematician would argue they are just as real as the typical flat geometry you know and love (or hate). These alternative geometries can be practically useful too!

The images above show triangles in spherical geometry. Those aren’t triangles though! Oh but they are! A triangle is just a polygon enclosed by three lines. Looks like it fits the criteria. Wait but those aren’t lines, they are curved! Ah yes. I argue that these are, for all intents and purposes, just as good as lines. We need to ask: What is a line? A line is so basic to us we may not know how to describe it. I offer this definition: A line is the shortest path between 2 points. The 3 curves that make the triangle above are in fact the shortest paths from one vertex to the other on the surface of the sphere (they just so happen to be on circumferences of the sphere, which are often referred to as great circles). So it may be more useful to think of lines, in general, as length minimizing curves. In conclusion, we would consider the shape above to be a triangle as it is enclosed by 3 length minimizing curves on a surface.

Spherical geometry can be very useful; think about the Earth. To reduce travel time, airplanes would want to travel along great circles as they are the shortest paths from one place to another. Additionally, this type of thinking (rethinking straight lines as length minimizing curves) is central to Albert Einstein’s general theory of relativity.

read more at http://staffrm.io/@missnorledge/35H6cS1T52

More Posts from T-sci-eng and Others

5 years ago
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Okay, I’ve really missed talking about teratology.

These dogs have polydactyl, but what’s interesting is that the extra dew claws can move independently of one another and grip things. They’re only found on the hind feet giving the dogs a distinctly velociraptor look

The Beauceron is an ancient breed, and no one has a definitive answer of why they have these, but the prevailing theory is that they were bred to do a lot of rock climbing because they were used for herding and hunting over rocky mountainous terrain.

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7 years ago

Curves of constant width

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                                                    Source

The width of a circle is constant: its diameter.

But the circle is not the only shape that holds this pristine title. For instance let’s look at the Reuleaux triangle

Reuleaux triangle

A Reuleaux triangle is a shape formed from the intersection of three circular disks, each having its center on the boundary of the other two.

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The Reuleaux triangle is the first of a sequence of Reuleaux polygons, curves of constant width formed from regular polygons with an odd number of sides.

Some of these curves have been used as the shapes of coins

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To drill square holes.

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They are not entirely square, their edges are fillets i.e the edges are rounded and not sharp.

This animation offers a good insight as to why that is so.

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And in china, apparently on bicycles.

The man Guan Baihua shows his self-made multi-angle-wheel bicycle on May 6, 2009 in Qingdao of Shandong Province, China. Guan Baihua spent 18 months to complete this strange bicycle.

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Other shapes of constant width

There are other shapes of constant width beside the Reuleaux triangle ( that has been discussed in this post ), a whole bunch of them really. Do take a look at them. ( links below )

I will leave you guys with my favorite one.

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More:

If this post fascinated you, i strongly suggest you check these out. They go in-depth with the mathematics that underlies these curves and talk about other cool stuff:

An animation of non-circular rollers

Shapes and Solids of Constant Width - Numberphile  

Shapes of constant width

Reuleaux Polygons,           

Edit:

For those who are wondering if these are something that one would stumble upon on a regular basis. You may not find perfect ones but similiar ones definitely.

I found mine on a really old BMI calculator thingy. ( not sure what you would call it )

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Have fun exploring !

7 years ago

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

There’s one last complication to consider with fluctuating stresses. When we looked at the case of fully reversed stresses (that is, σ_m = 0, σ_a ≠ 0) we found a fatigue stress concentration factor based on the stress concentration factor for a static situation.

With a fluctuating stress, the situation is a little different. Since the mean stress is non-zero, the part is always under some kind of load. We can consider the effects of this constant mean stress separately from the effects of the momentary alternating stress and assign them a separate fatigue stress concentration factor, which we’ll call K_fm.

Let’s think about what’s actually physically happening to a part being subjected to a fluctuating stress. Let’s say we’re dealing with a plate with a slot in it subjected to fluctuating tension.

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

There’s obviously a large stress concentration at the slot that we’ll have to take into account.

There’s three different scenarios which can occur here. The first is that the maximum stress the plate sees (the largest value of combined mean and alternating stress, taking stress concentrations into account) never approaches the yield strength of the material. The plate just stretches and contracts elastically. This isn’t really any different from our previous situation with fatigue stress concentration factors - we can use the K_f factor we got earlier here.

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

But suppose the yield strength is exceeded. What happens then? If the maximum stress is greater than the yield strength, then the plate must deform plastically at that point of maximum stress - the slot must widen. If the slot is wider, then the stress concentration is relieved - there’s more room for movement before the geometry stops you. If other words, the fatigue stress concentration factor is lessened.

If it’s just your maximum stress that exceeds the yield strength but your minimum stress is still below it, this localized yielding will be one-sided - you’ll get a slot that’s widened on one side, but you’ll still have some overall mean stress. If this is the case, you base your stress concentration factor on the relationship of the mean and alternating stresses to the yield strength.

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

If both your minimum and maximum stresses exceed the yield strength of the material, you get a situation where you’ve widened the slot as far as you can without actually breaking the part on both sides and you’re experiencing a stress of magnitude equal to the yield strength at either extreme of the fluctuation. Since you now have a fluctuation with equal and opposite extremes, your mean stress is zero - the mean fatigue stress concentration factor is zero. The scenario is now one of fully reversed loading and the mean stress drops right out of it.

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

Dude, bullets are literally made to shatter on impact. It's to prevent over-penetration. Bullets frequently shatter if they hit human bone inside a body, for example. So congrats, a katana is as good at stopping bullets as a human bone. Or a regular butter knife. Or even a regular piece of old steel. Like the ones used in a target range. Ever wonder why the steel plates at target ranges don't have holes in them even tho rifle caliber bullets hit them? It's cause the bullet shatters on impact.

To be very clear, the intention of the post was never to say that Katana is the ultimate sword. It was merely to enlighten the possibility of the bullet getting shattered by a sword/Knife.

Yes, bullets do shatter on impact.

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But I am not so sure about what you say about the human bone though.

I believe it really depends on that kinetic energy of the bullet, the bullet size and the place of impact of the bullet on the body.

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And even with the tissues surrounding the bone, there have been many instances where the Femur ( thigh bone ) fractured on impact.

If anyone reading this has a background in the field, would highly appreciate to hear your stance on this.

Thanks for asking anon ! :D

7 years ago
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way
Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way

Are Cloaking Devices Coming? Metalens-Shaped Light May Lead The Way

“The biggest challenge facing a real-life cloak has been the incorporation of a large variety of wavelengths, as the cloak’s material must vary from point-to-point to bend (and then unbend) the light by the proper amount. Based on the materials discovered so far, we haven’t yet managed to penetrate the visible light portion of the spectrum with a cloak. This new advance in metalenses, however, seems to indicate that if you can do it for a single, narrow wavelength, you can apply this nanofin technology to extend the wavelength covered tremendously. This first application to achromatic lenses covered nearly the full visible-light spectrum (from 470 to 670 nm), and fusing this with advances in metamaterials would make visible-light cloaking devices a reality.”

What would it take to have a true cloaking device? You’d need some way to bend the light coming from all across the electromagnetic spectrum around your cloaked object, and have it propagate off in the same direction once it moved past you. To an outside observer, it would simply seem like the cloaked object wasn’t there, and they’d only view the world in front of and behind them. Even with the recent advances that have been made in metamaterials, we have not yet been able to realize this dream in three dimensions, covering the entire electromagnetic spectrum, and from all directions. But a new advance in metalens technology might get you the full electromagnetic spectrum after all, as they appear to have solved the problem of chromatic aberration with a light, small, and inexpensive solution. If we can combine these two technologies, metalenses and metamaterials, we just might realize the dream of a true invisibility cloak.

Whether you’re a Star Trek or Harry Potter fan, the ability to turn yourself invisible would be Earth-shattering. Come see how transformation optics might transform the world!


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7 years ago
I Have Always Been Fascinated By Pokemon.

I have always been fascinated by Pokemon.

Tiding through the waves of time, now that I think about it : Pokemon did teach me a lot about physics, especially electricity. 

What is Electricity ?

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Electricity stems from a potential difference between two areas, which allows for electromotive force to ensue in mobile electrons.

Bio-electricity

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In biological cells, a voltage imbalance or a cell potential difference exists between the inside and outside of a a cell.

The cell achieves this by removing 3 sodium ions for every 2 potassium ions allows into the system. The removing process consumes energy ( ATP ).

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                               The sodium ions leaving the cell 

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                            The Potassium ions entering the cell

Source Video

Pikachu and Bioelectrogenesis

Where does pikachu gets it’s electrical powers ? 

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Its by a process known as bioelectrogenesis.

Bioelectrogenesis is the generation of electricity by living organisms

How it works is rather blunt. Remember I told you that the cells are maintained in a potential difference.

There are passageways /electrolytes that are present that allows a flow of ions through them.

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                                            Ion Passageways

When required, the brain of the pikachu sends a signal through the nervous system to these electrolytes, opening ions channels and reversing charge polarity, causing an abrupt difference in electric potential.

The final effect is the generation of electric current, capable of going up to 100,000 Volts during its thunderbolt move.

Result : Opponent stupefied.

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Water is better conductor than air

Most of animals that bioelectrogenic in nature are aquatic creatures ( electric eels, rays, cattlefish, etc ) . This is because water is a much better electrical conductor than air, therefore electrical signals signals can be transmitted through water.

This betters the chance for the organism to protect itself against predators. Pikachu is not aquatic because probably the writes didn’t want it be so - Poetic License ;P

More:

Some other pokemons that were also bioelectrogenic  were: Eelektrik and the Eelektross

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The voice of Pikachu - must watch

Electrogenic Humans

The one that ash has is a male pikachu. There is a female to the species as well. ( Look at the tail )

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That’s pokemon physics for you folks.

Hope you enjoyed reading this post as much i did drafting it. Oh boy! There is physics just in about everything !

7 years ago
Adieu 2016 - Best Of FYP!

Adieu 2016 - Best of FYP!

2016 has been a great year for FYP!

And we would like to conclude it with some of the best posts that we have been able to produce

1. Black hole are not so black - series

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Part - I , II, III

2.‘Katana’ - A sword that can slice a bullet

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3. A denied stardom status - Jupiter

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4. The Pythagoras Cup

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5. On Pirates and Astronomers                                                           

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6. Behold- The Space Shuttle Tile

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7. Principle of Least Effort

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8. Leidenfrost Effect

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9. Major Types of Engines

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10. A holy matrimony of Pascals and Sierpinski’s Triangle

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11. Curves of constant width

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12. Smooth Ride, Bumpy Road

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Thank you so much following us ! Have a great weekend :D

 - Fuck Yeah Physics!

7 years ago
Sound waves could take a tsunami down a few notches
A tsunami’s ferocious force could be taken down a few notches with a pair of counter waves.

Fight waves with more waves!

A tsunami’s immense wall of water may not be stoppable. But there may be a way to take the ferocious force of nature down a few notches, using a pair of counterwaves.

If released at the right moment, a type of sound wave known as an acoustic-gravity wave could subdue a tsunami, applied mathematician Usama Kadri of Cardiff University in Wales reports January 23 in Heliyon. These acoustic-gravity waves, which reach deep below the ocean’s surface, can stretch tens or hundreds of kilometers and easily travel long distances at high speeds.

7 years ago
Students Fortify Concrete By Adding Recycled Plastic

Students fortify concrete by adding recycled plastic

Adding bits of irradiated plastic water bottles could cut cement industry’s carbon emissions

Discarded plastic bottles could one day be used to build stronger, more flexible concrete structures, from sidewalks and street barriers, to buildings and bridges, according to a new study.

MIT undergraduate students have found that, by exposing plastic flakes to small, harmless doses of gamma radiation, then pulverizing the flakes into a fine powder, they can mix the plastic with cement paste to produce concrete that is up to 20 percent stronger than conventional concrete.

Concrete is, after water, the second most widely used material on the planet. The manufacturing of concrete generates about 4.5 percent of the world’s human-induced carbon dioxide emissions. Replacing even a small portion of concrete with irradiated plastic could thus help reduce the cement industry’s global carbon footprint.

Reusing plastics as concrete additives could also redirect old water and soda bottles, the bulk of which would otherwise end up in a landfill.

Read more.

7 years ago
A Sponge Can’t Soak Up Mercury. (Video) Facebook | Instagram | Scary Story Website

A sponge can’t soak up mercury. (Video) Facebook | Instagram | Scary Story Website

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