fuckyeahphysica:

The Katana is a Japanese sword that was used by the samurai in Japan. Curved, slender, single-edged blade with a circular or squared guard and a long grip to accommodate two hands are the characteristics of a katana.

This sword has been in my field of obsession for the past few days and primary reason for that is this truly remarkable fact:

It can slice a moving bullet in half

image

                                               Source Video

Its not often that you find a bullet’s reputation of being rigid taking a
hit.

But I am not here to deceive, the above is in reality a Katana
slicing a bullet in half.

What makes it so strong?

Its strength is attributed to its extensive manufacturing procedure. And for very good reasons, the legit ones cost thousands of dollars.( and antique ones, will ensure a hole in your pocket )

Here’s how a katana is crafted:

Iron-sand is a type of sand that has high concentrations of Iron ( -_- ) and since its contains magnetite, it is also magnetic is nature.

image

                                          

Source

This Iron sand is heated in a conventional furnace to 1400 C and maintained at that temperature for three whole days ! This is done in order to even out the carbon content in the steel.

Eventually a lump of iron known as tamahagane emerges on immersing it in water.

image

                                                Source

The best ones are chosen, pounded flat and arranged in stacks. Depending on the style of the Katana, different layers of soft, medium and hard steel are used.

image

The resultant material is heated again and flattened out.

This process : Bending, hammering, layering and repeat , is carried out several times.

image

A long block of steel emerges from this procedural, which is only slightly curved. To impart the curvature and also strengthen the sword even more, a wet clay coating is applied.

image

                                                Source

The edge of the blade is coated with a thinner layer than the
sides and spine of the sword. This causes only the
blade’s edge to be hardened and also causes the blade to curve due to
the difference in densities of the micro-structures in the steel.

The coated sword is heated and then quenched in water ( immersed immediately in water / rapid cooling ).

image

Now the sword has the endurance and the strength, it is time to polish the katana. Polishing is an art by itself and requires the most skilled smiths. The process of polishing takes between one and three weeks.

The polisher uses finer and
finer grains of polishing stones in a process called glazing, until the
blade has a mirror finish. 

image

A Katana emerges out of the procedural, having faced the hammering and the heat – strong, sturdy and powerful.

And it is this remarkable man-made masterpiece that has the potency to slice through a bullet.

The Philosophy

image

Japan considering its cultural and philosophical background does not consider the sword merely to be a weapon but also as an art-craft. The Sword, per se is only to be drawn for protection and uphold justice.

In fact, the most experienced masters of the art are ones who defeat their opponent without drawing their swords. And this can be attained when one is in touch with the peace within their heart. That’s the ultimate goal !


EDIT:

Anonymous has pointed out that there is no picture of the actual katana in the entire post. My bad, I am sorry ! Here you go:

The Katana is a Japanese sword that was used by the samurai in Japan. Curved, slender, single-edged blade with a circular or squared guard and a long grip to accommodate two hands are the characteristics of a katana.

This sword has been in my field of obsession for the past few days and primary reason for that is this truly remarkable fact:

It can slice a moving bullet in half

image

                                               Source Video

Its not often that you find a bullet’s reputation of being rigid taking a
hit.

But I am not here to deceive, the above is in reality a Katana
slicing a bullet in half.

What makes it so strong?

Its strength is attributed to its extensive manufacturing procedure. And for very good reasons, the legit ones cost thousands of dollars.( and antique ones, will ensure a hole in your pocket )

Here’s how a katana is crafted:

Iron-sand is a type of sand that has high concentrations of Iron ( -_- ) and since its contains magnetite, it is also magnetic is nature.

image

                                          

Source

This Iron sand is heated in a conventional furnace to 1400 C and maintained at that temperature for three whole days ! This is done in order to even out the carbon content in the steel.

Eventually a lump of iron known as tamahagane emerges on immersing it in water.

image

                                                Source

The best ones are chosen, pounded flat and arranged in stacks. Depending on the style of the Katana, different layers of soft, medium and hard steel are used.

image

The resultant material is heated again and flattened out.

This process : Bending, hammering, layering and repeat , is carried out several times.

image

A long block of steel emerges from this procedural, which is only slightly curved. To impart the curvature and also strengthen the sword even more, a wet clay coating is applied.

image

                                                Source

The edge of the blade is coated with a thinner layer than the
sides and spine of the sword. This causes only the
blade’s edge to be hardened and also causes the blade to curve due to
the difference in densities of the micro-structures in the steel.

The coated sword is heated and then quenched in water ( immersed immediately in water / rapid cooling ).

image

Now the sword has the endurance and the strength, it is time to polish the katana. Polishing is an art by itself and requires the most skilled smiths. The process of polishing takes between one and three weeks.

The polisher uses finer and
finer grains of polishing stones in a process called glazing, until the
blade has a mirror finish. 

image

A Katana emerges out of the procedural, having faced the hammering and the heat – strong, sturdy and powerful.

And it is this remarkable man-made masterpiece that has the potency to slice through a bullet.

The Philosophy

image

Japan considering its cultural and philosophical background does not consider the sword merely to be a weapon but also as an art-craft. The Sword, per se is only to be drawn for protection and uphold justice.

In fact, the most experienced masters of the art are ones who defeat their opponent without drawing their swords. And this can be attained when one is in touch with the peace within their heart. That’s the ultimate goal !


The Miura Fold

.

The Miura fold is a method of folding a flat surface such as a sheet of paper into a smaller area. The fold is named for its inventor, Japanese astrophysicist Koryo Miura.

Why it is awesome?

The Miura fold is a form of rigid origami, meaning that the fold can be carried out by a continuous motion in which, at each step, each parallelogram is completely flat.

This property allows it to be used to fold surfaces made of rigid materials; for instance, it has been used to simulate large solar panel arrays for space satellites in the Japanese space program.

The fold can also be unpacked in just one motion by pulling on opposite ends of the folded material, and likewise folded again by pushing the two ends back together.

In the application to solar arrays, this property reduces the number of motors required to unfold this shape, reducing the overall weight and complexity of the mechanism.

Other cool stuff.

Miura folded maps. Snug it into your pocket when not in need and open it up in style when you are lost !

image

(Source : http://www.bun-sho-do.co.jp/english/nextg/miura-fold/ , wikipedia )