science

Ratl

Ratl 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 Ratl rather than just read about it. In short: A ratl (رطل ) is a medieval Middle Eastern unit of measurement found in several historic recipes. The term was used to measure both liquid and weight (around a pound and a pint in 10th century Baghdad, but anywhere from 8 ounces to 8 pounds depending on the time period and region).

Key takeaways

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

Reference excerpt

A ratl (رطل ) is a medieval Middle Eastern unit of measurement found in several historic recipes. The term was used to measure both liquid and weight (around a pound and a pint in 10th century Baghdad, but anywhere from 8 ounces to 8 pounds depending on the time period and region). While there were a variety of names for different shapes of cups and mugs in use at the time, the ratl seems to have had a position roughly equivalent to a British pint in that the name of the drinking-vessel also implied a standardized measurement as opposed to merely the object's shape, in both 10th century Baghdad and 13th century Andalusia. However, those standardized measures varied both by region and by purpose: the spice-measuring ratl, the flax-measuring ratl, the oil-measuring ratl, and the quicksilver-measuring ratl all differed from each other. The ratl was a part of a sequence of measurements ranging from a grain of barley through the dirham (used as a common point of reference in both medieval European and Middle Eastern regions) on up to the Sa (Islamic measure).

measurement 1 Mudd = 8/6 ratl 1 Sá = 4 mudd = 5+1/3 ratl. 1 Ratl = 128+4/7 dirham or 128 dirham or 130 dirham. 1 Uqiyyah = 40 dirham. 1 Nashsh = 20 dirham. 7 mithqal = 10 dirham. 1 mithqal = 72 grains of average barely both edges cut. 1 mithqal = 20 qirat قِيراط of makkah = 21+3/7 qirat of Damascus. 1 Dirham = 0.7 mithqal =14 qirat of makkah = 15 qirat of Damascus. 1 mil = 4000 zira. 1 wasq = 60 sá. In al-Warraq's tenth-century cookbook, different regions used some of the same terms to mean different units of measurement and the relationships between them. Some of those relationships are described below.

References

Worked examples

Example 1 — a first encounter with Ratl

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

In research: Ratl 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 Ratl 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: Ratl is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cooking weights and measures, Customary units of measurement, Standards and measurement stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Ratl 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 Ratl in 20 minutes

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

Frequently asked questions

What is Ratl in simple terms?

Why does Ratl 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 Ratl?

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 Ratl.