physics

MR 31

MR 31 is a physics 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 MR 31 rather than just read about it. In short: The MR 31 was a French nuclear warhead for the S2 medium-range ballistic missile. The weapon had a yield of 120 kilotonnes of TNT (0.50 PJ) and weighed 700 kilograms (1,500 lb).

Key takeaways

MR 31 belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MR 31 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MR 31 from memory before moving on to harder problems.

Reference excerpt

The MR 31 was a French nuclear warhead for the S2 medium-range ballistic missile. The weapon had a yield of 120 kilotonnes of TNT (0.50 PJ) and weighed 700 kilograms (1,500 lb). It was apparently a pure plutonium device and unboosted, and the largest pure plutonium weapon ever built. Entering service in August 1970 it was withdrawn from service by June 1980.

See also force de frappe FOST nuclear tests by France

References

Worked examples

Example 1 — a first encounter with MR 31

Start with the simplest possible case. Write down what MR 31 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 MR 31 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 MR 31 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 MR 31

In research: MR 31 appears in physics 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 MR 31 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: MR 31 is common in secondary-school and first-year university syllabi. It links to neighbouring topics French military stubs, Military equipment introduced in the 1970s, Nuclear warheads of France, so understanding it makes those chapters shorter.
In everyday life: Look for MR 31 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 MR 31 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MR 31 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 MR 31 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MR 31 in simple terms?

The MR 31 was a French nuclear warhead for the S2 medium-range ballistic missile. The weapon had a yield of 120 kilotonnes of TNT (0.50 PJ) and weighed 700 kilograms (1,500 lb).

Why does MR 31 matter?

Because it connects several physics 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 MR 31?

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 MR 31.