science

Li (mass)

Li (mass) 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 Li (mass) rather than just read about it. In short: Li (simplified Chinese: 厘; traditional Chinese: 釐; pinyin: lí), called lei in Cantonese, ly in Vietnamese or "cash" in English, is a traditional Chinese unit for weight measurement. It originated in China before being introduced to neighboring countries in East Asia.

Key takeaways

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

Reference excerpt

Li (simplified Chinese: 厘; traditional Chinese: 釐; pinyin: lí), called lei in Cantonese, ly in Vietnamese or "cash" in English, is a traditional Chinese unit for weight measurement. It originated in China before being introduced to neighboring countries in East Asia. Nowaday, the mass of 1 li equals 50 mg (i.e., 0.05 grams) in mainland China, 37.5 mg in Taiwan, 37.8 mg in Hong Kong, Singapore and Malaysia, and 37.8 mg in Vietnam. Li is mostly used in the traditional markets.

China Mainland On June 25, 1959, the State Council of the People's Republic of China issued the "Order on the Unified Measurement System", retaining the market measure system, with minor amendment.

where 1 li equals 50 mg or 0.05 grams, and 10 li equals 1 fen.

Taiwan The Taiwanese still use the old weights and measures of the Chinese Qing Dynasty. 1 Taiwan li is equal to 37.5 mg, or 1/10 Taiwan fen.

Hong Kong and Macau In Hong Kong, one li is equal to 1/10 fen, which is 37.799 mg or 0.037799 grams.

Singapore and Malaysia have similar regulations as Hong Kong, as they are all former British colonies.

Vietnam In Vietnam, 1 li or ly is equal to 37.8 mg (i.e., 0.038 grams) or 1/10 fen by traditional value.

For more information on the Chinese mass measurement system, please see article Jin (mass).

See also Chinese units of measurement Hong Kong units of measurement Taiwanese units of measurement Vietnamese units of measurement

References

External links 中國度量衡#衡市制厘 (質量單位)

Worked examples

Example 1 — a first encounter with Li (mass)

Start with the simplest possible case. Write down what Li (mass) 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 Li (mass) 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 Li (mass) 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 Li (mass)

In research: Li (mass) 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 Li (mass) 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: Li (mass) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chinese units of measurement, Customary units of measurement, Units of mass, so understanding it makes those chapters shorter.
In everyday life: Look for Li (mass) 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 Li (mass) in 20 minutes

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

Frequently asked questions

What is Li (mass) in simple terms?

Why does Li (mass) 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 Li (mass)?

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 Li (mass).