science

Kamifūsen

Kamifūsen 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 Kamifūsen rather than just read about it. In short: The term kamifūsen (紙風船; literally: "paper balloon") refers to several types of paper balloons in Japanese culture. They are simple toys for children, advertising give-aways for traditional medicine companies, and illuminated flying balloons at festivals.

Key takeaways

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

Reference excerpt

The term kamifūsen (紙風船; literally: "paper balloon") refers to several types of paper balloons in Japanese culture. They are simple toys for children, advertising give-aways for traditional medicine companies, and illuminated flying balloons at festivals. Smaller kamifūsen are popular as traditional children's toys in Japan. These have an open hole, and reinflate as they are bounced in play. The balloon is made of glassine paper known as washi, which is air-resistant, glossy and thin, and which has sufficient plasticity to allow it to be formed into a new shape, which it can then retain. The properties of these paper balloon toys are of interest to scientists.

Traditionally, kamifūsen were sold in dagashiya, small shops selling candy, snacks and inexpensive toys to schoolchildren as an alternative to the more expensive rubber balloon. They are now sold in souvenir shops and online. Another variation, known as the kakufūsen (角風船; literally: "angled balloon") is in the shape of a cube rather than a sphere, and is associated with the marketing campaigns of traditional medicine companies. Much larger kamifūsen, resembling sky lanterns, are flown each year at the Kamihinokinai Paper Balloon Festival (上桧木内の紙風船上げ) in Semboku, Akita.

Physics Toy kamifūsen display some counterintuitive properties that have been studied by scientists. Even though they have an open hole, they tend to inflate rather than deflating when bounced up by a person's hands. According to Ichiro Fukumori of the Jet Propulsion Laboratory, "Despite the open hole visible in the silver patch, the kamifūsen stays inflated when bounced on the palm of one’s hand. Moreover, repeated bouncing causes a deflated kamifūsen to swell by itself to its fully inflated condition. The elastic rebound of the balloon paper is not enough to explain the full inflation; a batted kamifūsen actually sucks in air from the atmosphere."

Variations

Some kamifūsen intended for decoration are made in the shapes of animals, birds and fruits. A kakufūsen (角風船) (kaku means "angled") is a paper balloon in the shape of a cube rather than a sphere, often used for commercial marketing purposes. Door-to-door salesmen called baiyaku-san (売薬さん) from the traditional medicine companies of Toyama used to give out kakufūsen printed with drug company advertising. Small chests filled with various medicines and bandages were left at no initial cost with customers, and the salesman would return from time to time, to restock the cabinet and collect payment. This system of "use first, pay later" marketing of medicines is called "okigusuri".

The Kamihinokinai Paper Balloon Festival (上桧木内の紙風船上げ) is held in Semboku, Akita, on February 10 each year. Hundreds of very large hot-air kamifūsen, resembling sky lanterns, are flown for good luck in the coming year. The festival has mythical origins, and was suspended during World War II. It was revived in 1974. According to tradition, Hiraka Gennai (1728–1780), a scientist in the Edo era, introduced paper balloons as markers for the copper mines in the mountains of the region, and also as entertainment.

In Japanese culture Two major Japanese films have featured kamifūsen in their titles. Humanity and Paper Balloons (人情紙風船, Ninjō Kami Fūsen) is an acclaimed 1937 drama film, and Torasan and a Paper Balloon (男はつらいよ寅次郎紙風船, Otoko wa Tsurai yo: Torajirō Kamifūsen) is a 1981 comedy.

See also Fu-Go balloon bomb Paper lantern Sky lantern

References

Further reading Barrett, Timothy (2005). Japanese Papermaking: Traditions, Tools, Techniques. Floating World Editions. ISBN 9781891640261.

External links Base Camp Math: How to Inflate a Paper Kamifusen Balloon:Tadashi Tokieda, Professor of Mathematics at Stanford University, illustrates and explains how a toy paper ball can be inflated without being blown up. (video)

Illustrations

Worked examples

Example 1 — a first encounter with Kamifūsen

Start with the simplest possible case. Write down what Kamifūsen 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 Kamifūsen 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 Kamifūsen 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 Kamifūsen

In research: Kamifūsen 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 Kamifūsen 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: Kamifūsen is common in secondary-school and first-year university syllabi. It links to neighbouring topics Balloons, Inflatable manufactured goods, Japanese crafts, so understanding it makes those chapters shorter.
In everyday life: Look for Kamifūsen 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 Kamifūsen in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kamifūsen 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 Kamifūsen out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kamifūsen in simple terms?

Why does Kamifūsen 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 Kamifūsen?

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 Kamifūsen.