science

Katana

Katana is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Katana rather than just read about it. In short: A katana (刀, かたな; lit. 'one-sided blade') is a Japanese sword characterized by a curved, single-edged blade with a circular or squared guard and long grip to accommodate two hands. Developed later than the tachi, it was used by samurai in feudal Japan and worn with the edge facing upward.

Key takeaways

Katana belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Katana to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Katana from memory before moving on to harder problems.

Reference excerpt

A katana (刀, かたな; lit. 'one-sided blade') is a Japanese sword characterized by a curved, single-edged blade with a circular or squared guard and long grip to accommodate two hands. Developed later than the tachi, it was used by samurai in feudal Japan and worn with the edge facing upward. Since the Muromachi period, many old tachi were cut from the root and shortened, and the blade at the root was crushed and converted into a katana. The specific term for katana in Japan is uchigatana (打刀, うちがたな; lit. 'striking sword') and the term katana (刀) often refers to single-edged swords from around the world.

Etymology and loanwords

The word katana first appears in Japanese in the Nihon Shoki of 720. The term is a compound of kata ("one side, one-sided") + na ("blade"), in contrast to the double-sided tsurugi. The katana belongs to the nihontō family of swords, and is distinguished by a blade length (nagasa) of more than 2 shaku, approximately 60 cm (24 in). Katana can also be known as dai or daitō among Western sword enthusiasts, although daitō is a generic name for any Japanese long sword, literally meaning "big sword". As Japanese does not have separate plural and singular forms, both katanas and katana are considered acceptable forms in English. Pronounced [katana], the kun'yomi (Japanese reading) of the kanji 刀, originally meaning single edged blade (of any length) in Chinese, the word has been adopted as a loanword by the Portuguese. In Portuguese the designation (spelled catana) means "large knife" or machete.

Description

The katana is generally defined as the standard sized, moderately curved (as opposed to the older tachi featuring more curvature) Japanese sword with a blade length greater than 60.6 cm (23.86 inches) (over 2 shaku). It is characterized by its distinctive appearance: a curved, slender, single-edged blade with a circular or squared guard (tsuba) and long grip to accommodate two hands. With a few exceptions, katana and tachi can be distinguished from each other, if signed, by the location of the signature (mei) on the tang (nakago). In general, the mei should be carved into the side of the nakago which would face outward when the sword was worn. Since a tachi was worn with the cutting edge down, and the katana was worn with the cutting edge up, the mei would be in opposite locations on the tang. Western historians have said that katana were among the finest cutting weapons in world military history. However, the main weapons on the battlefield in the Sengoku period in the 16th century were yumi (bow), yari (spear), and tanegashima (gun), and katana and tachi were used only for close combat. During this period, the tactics changed to a group battle by ashigaru (foot soldiers) mobilized in large numbers, so naginata and tachi became obsolete as weapons on the battlefield and were replaced by yari and katana. In the relatively peaceful Edo period, katana increased in importance as a weapon, and at the end of the Edo period, shishi (political activists) fought many battles using katana as their main weapon. Katana and tachi were often used as gifts between daimyo (feudal lord) and samurai, or as offerings to the kami enshrined in Shinto shrines, and symbols of authority and spirituality of samurai.

History

The production of swords in Japan is divided into specific time periods:

Jōkotō (ancient swords, until around 900) Kotō (old swords from around 900–1596) Shintō (new swords 1596–1780) Shinshintō (newer swords 1781–1876) Gendaitō (modern or contemporary swords 1876–present)

Kotō (Old swords)

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Katana

Start with the simplest possible case. Write down what Katana claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Katana before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Katana ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Katana

In research: Katana appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Katana in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Katana is common in secondary-school and first-year university syllabi. It links to neighbouring topics Japanese inventions, Japanese sword types, Samurai swords, so understanding it makes those chapters shorter.
In everyday life: Look for Katana outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Katana in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Katana means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Katana out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Katana in simple terms?

Why does Katana matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Katana?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Katana.