Mechanics 1
Vocabulary Precision List
Provenance: written 2026-09-29, built directly from research/veridian/WME01-verified-facts.md (17 series, Oct 2018–Jun 2025) and cross-checked against the nine curriculum lesson files in content/veridian/curriculum/wme01/ and the rest of content/veridian/technique-hub/wme01/ (the CODEX formula bank, the FORGE exam-technique guide, the battle card, and the SIGNAL topic briefs) so nothing below repeats a distinction those files already own. No new primary-source PDF was fetched for this pass; every claim traces to a fact already verified against a real Pearson mark scheme, examiner report, or specification PDF in the facts bank, quoted here at no more than a short fragment with the rest paraphrased. Two abbreviations in Pearson's own general list (bod, awrt) have no confirmed live WME01 instance anywhere in this course's research — that gap is stated where it occurs rather than filled with an invented example.
FORGE · WME01 Vocabulary Precision List
Pearson Edexcel IAL Mechanics 1 (WME01/01) — the words the mark scheme is precise about
Every other document in this hub teaches a topic, a paper shape, or a formula. This one teaches neither. It is a list of specific words and short phrases — some mark-scheme shorthand, some ordinary-looking English inside a question stem — where the exact word used, or the exact word a candidate writes back, is the entire difference between a mark banked and a mark lost, verified against real WME01 mark schemes and examiner reports rather than assembled from a general sense of "exam technique." Where a fuller worked treatment of the same idea already exists elsewhere in this hub, that is named rather than repeated.
1. Mark-scheme code vocabulary
The general definitions below are Pearson's own, confirmed word-for-word identical across every mark scheme's "General Marking Guidance" and "General Abbreviations" pages checked for this course (MS_Jan2023, MS_Jan2024, MS_Oct2023). What follows each definition is the part that actually matters for a candidate: a real instance of the code in use, where one has been found in this course's research, or an honest note that none has, rather than a guess.
M, A, B, DM — already fully treated elsewhere, named here for completeness only
M (method), A (accuracy, dependent on the M it follows), B (independent accuracy, no method needed), and DM (a method mark dependent on an earlier, specific, named method mark) are explained in full, with worked instances, in forge-exam-technique-guide.md §2 and the formula bank's §2.8. Not repeated here beyond one precision point that belongs in a vocabulary list specifically: DM is not a stronger or "extra" mark, it is dep (dependent) applied to a method mark rather than an accuracy one — the same generic idea Pearson's own abbreviation list uses for dep/indep below, just named DM when the thing being made dependent is a method step rather than a final value.
isw — ignore subsequent working
Definition, confirmed verbatim: once a mark is earned, wrong working after that point does not take it away. This is not a vague leniency policy; it is written into specific mark-scheme lines. Three real instances found in this course's research: MS_Jun2024 Q4(a) attaches isw directly to the line RC = 5.2g; MS_Oct2020's own accuracy line reads "correct answer (isw if they find the magnitude)" — i.e. the mark survives even if the candidate goes on to compute something else afterward; MS_Oct2023 Q4(a) attaches isw to a two-term vector sum. The precision that costs marks when blurred: isw protects an already-correct line from later damage — it does not create credit for a line that was wrong to begin with, and it does not apply retroactively to an earlier, separate part of the working.
SC — special case
Definition, confirmed verbatim: a pre-written exception, stated in the mark scheme itself, granting credit for one specific alternative (often a specific "wrong" setup) that would not otherwise be creditable under the general marking rules. Real instance: MS_Jun2019's friction question states "condone if P acting in the wrong direction but see SC below," followed by a line awarding "SC if F opposes their P, 6/6 available." The precision point: an SC is not a general "credit sensible alternatives" licence — it is scoped to the exact configuration Pearson wrote down in advance for that one question. A candidate's own different wrong setup, however reasonable-looking, is not covered by an SC written for a different one.
oe and ft — or equivalent, and follow-through
Definition, confirmed verbatim: oe accepts any algebraically equivalent form of a stated answer; ft allows a later mark to be earned using the candidate's own earlier value, even if that earlier value was itself wrong. Real instance, both in the same line: MS_Jan2023 Q1(c) awards M1 for "20 = a × their T oe" and then A1 ft for the acceleration that follows from it. The precision point, easy to blur in the wrong direction: ft rescues an accuracy mark built on a wrong earlier value — it does not retroactively fix the method mark that produced the wrong value in the first place, and it does not apply to a mark the scheme has not explicitly flagged ft.
cso versus a "show that" / given-answer mark — genuinely easy to conflate, and genuinely different
Definition, confirmed verbatim: cso (correct solution only) means the accuracy mark can only be awarded if the working in that part of the question contains no errors at all, not merely that the final number happens to be right. It is tempting to assume cso is the tag that makes a "show that" question strict. It is not, and the primary-source record shows this directly: in the one WME01 paper this course has audited mark-code-by-mark-code for this exact question (Oct 2019 WME01), cso is attached to Q2(b), an ordinary find-the-value part (the answer h = 0.625 m) — not to either of that same paper's two genuine given-answer parts, Q4(a) and Q4(b), which instead carry the mark scheme's own separate given-answer annotation (elsewhere in this same series' record, Jan 2023 uses the equivalent tag A1*, described in that scheme as "reaches given answer from correct working"). The distinction that costs marks when blurred, stated the other way round from how a candidate usually meets it: a cso mark can be lost on an ordinary find-the-value question if any line of working is wrong, even a line that plays no role in the final number, exactly as strictly as a "show that" question is marked — but the tag itself is not exclusive to "show that" questions, and a "show that" question's own given-answer mark is a different mark type with its own name, not cso under another guise.
cao — correct answer only
Definition, confirmed verbatim: no method credit is available separately from the final value; the accuracy mark stands or falls on the number alone. Real instance: MS_Jan2022 Q6(a) — after two method-and-accuracy lines for the two component equations — closes the part with a final A1 marked cao, applied only once both unknowns (p = −6, q = 4) are correct. The precision point: cao marks the last link in a chain that already had its own separate method credit earlier in the same part — it is not a signal that the whole part is unmarked for method, only that this specific closing line is not.
dep / indep, and dp / sf — the two abbreviation pairs with no confirmed WME01 instance in this course's research
Pearson's own general abbreviations list defines dep/indep (dependent/independent, the general form DM is a specific case of) and dp/sf (decimal places/significant figures) in exactly the terms already used above and in forge-exam-technique-guide.md's rounding rule (g = 9.8, final answers to 2 or 3 sf, penalised once per question if over- or under-accurate, but premature rounding penalised every time it occurs). No mark-scheme line using the literal abbreviation dp or sf, or a standalone indep tag, has turned up in the primary-source excerpts this course has actually pulled and read for WME01 — only the underlying rounding rule has a confirmed real citation, not the two-letter code itself in use on a specific question. Recorded here honestly rather than manufactured, per this document's own standing rule against inventing an instance to fill a gap. The same is true of bod (benefit of the doubt) and awrt (answer which rounds to): both are genuine, verbatim entries in every mark scheme's general abbreviations page, and neither has a confirmed specific WME01 line attached to it anywhere in this course's research to date.
2. Command-word and technical-term pairs the mark schemes are precise about
"Show that" versus "hence show that"
The distinction: a plain "show that" accepts any valid, complete method reaching the stated result. "Hence show that" additionally requires the candidate to actually use an earlier part of the same question — a fresh, independent derivation of the same result, however correct, does not satisfy "hence." Grounded directly: five separate series (Jan 2020, Jan 2023, Oct 2022, Jun 2024, Oct 2023) repeat some form of the same standing instruction, confirmed verbatim in this course's research as "a full explanation, including all steps, is required to earn full marks" for this command-word family, with the "hence" case additionally requiring that the explanation draw on one or more previous parts rather than a self-contained restart. A related, separately-confirmed precision rule on the same command word: where a "show that" target is a specific fraction rather than a decimal, Pearson's own Jun 2025 friction question requires the working to stay in exact fractions throughout — a decimal substituted mid-chain, even one that rounds correctly, breaks the chain and costs the final mark (full detail: forge-exam-technique-guide.md §4).
"About to tilt" / "on the point of tilting"
The distinction: this phrase names the support the rod is tilting about — the support that stays in contact — not the support nearer the added load, and not an invitation to zero whichever reaction looks easiest. The reaction that actually goes to zero belongs to the other support. Grounded directly, two independent series: Jan 2023 Q4's examiner report states plainly that "about to tilt" implied one of the reactions had to be zero, and separately records candidates who zeroed the wrong one; Jun 2024 Q4 rewards the candidates who read the phrase correctly, "took moments about C," producing "an equation with M as the only unknown" — the efficient method the phrase itself points to once read precisely. Full worked treatment: codex-deep-dive-moments-rods-on-two-pivots.md; named here only for the phrase-level precision.
"F = μR" versus "F ≤ μR" — which formula a phrase in the stem actually licenses
The distinction is written into the specification itself, in two separate sub-points with two deliberately different verbs: spec 4.4 gives "an understanding of F = μR when a particle is moving," and spec 5.3 separately gives "an understanding of F ≤ µR in a situation of equilibrium." The equals sign is not a simplification of the inequality — it is only ever true at the specific instant a particle is moving, or is on the point of moving ("limiting equilibrium," "on the point of sliding/slipping"). Away from that instant, in ordinary equilibrium, friction takes whatever value resolving the other forces requires, which can be anything up to but not equal to μR. Grounded directly: Oct 2022 Q3 is built as exactly this two-part test — part (a) requires showing that no frictional force acts at all under the stated numbers (F = 0, nowhere near the limiting value), and part (b) moves the same scenario to the limiting boundary where F = μR genuinely applies — the same rough plane, deliberately split by the examiners to test whether a candidate reads the physical situation rather than reaching for F = μR by default the moment friction is mentioned.
Weight versus mass
The distinction: weight (W = mg) is a force, in newtons; mass (m) is measured in kilograms and is not itself a force. Grounded directly: Jan 2022 Q1's examiner report records that "weight [was] confused with mass, resulting in the use of 5g" — i.e. candidates took a force already correctly given in newtons and multiplied it by g a second time, manufacturing an extra, incorrect factor from treating a newton value as if it were a mass in kilograms. Full worked treatment: codex-deep-dive-equilibrium-of-a-particle-coplanar-forces.md.
A modelling term ("light rod") versus the equilibrium condition it has nothing to do with
The distinction: "modelling the beam as a rod" is a statement about what the object is assumed to be (rigid, and — if also described as light — massless); "clockwise moments equal anticlockwise moments" is a statement about the forces acting on it in a specific equilibrium situation. The two sentences can both be true in the same question without either one being an answer to the other's question. Grounded directly: Jan 2020 Q2(b) asked what modelling a beam as a rod means, and the examiner report records that the most common wrong answers were exactly this substitution — candidates writing "clockwise moments equal anticlockwise moments" (an equilibrium fact) where the credited answer was about the rod's own rigidity and mass (a modelling fact). The two ideas sit one topic apart in the spec (1.1 versus 6.1) and share no vocabulary in the mark scheme, which is precisely why the conflation is a real, reported error rather than a hypothetical one.
Speed versus velocity, and a vector versus its magnitude — named here for completeness, not re-argued
Both of these are already the single most heavily evidenced precision points in this course's WME01 research, with full worked treatment in momentum-impulse-sign-convention.ts, forge-exam-technique-guide.md §4, and codex-deep-dive-newtons-second-law-in-vector-form.md. Stated here only in the compressed, sourced form a vocabulary list is for: "speed" and "magnitude" are never negative and never a bare vector — report the unsigned size only. "Velocity" keeps whatever sign the working produced. Three independent series record the identical last-mark loss for reporting a signed value where speed was required — Jan 2020 ("not taking account of the direction of the velocity"), Oct 2022 ("the final answer needed to be positive as speed was required"), Jun 2024 ("the final mark was often lost because it had been left as negative") — and Jan 2025 independently records the mirror-image error, a fully correct vector answer left as "a vector instead of finding the magnitude." A genuinely two-sided nuance worth stating precisely rather than as a blanket rule: Jan 2025 Q5(a) asked for a velocity, and candidates who answered with an unsigned speed instead were not penalised for it — the word in the question decides which one is required, in either direction, and that word can change between parts of the very same question.
"In terms of mg" — a symbolic-answer instruction, not a stylistic preference
The distinction: where a connected-particles mark scheme states an answer "must be in terms of mg" (or "must be of form kmg"), a correct decimal number is not an equivalent, acceptable alternative — it is a different, non-credited answer to the same question. Grounded directly, two independent series enforcing the identical condition on the identical dependent mark: Jun 2024 Q3's mark scheme requires the solved tension "must be in terms of mg," with the accuracy mark specified as "any equivalent expression of the form kmg"; Jan 2022 Q7's mark scheme, independently, requires the tension "must be of form kmg" and states this "must be in terms of mg only." The precision point: this is not a general convention across every WME01 question with an algebraic mass — it is a specific instruction tied to the specific question that states it, and it only applies where the mark scheme actually says so.
3. What this document deliberately does not cover
No mark-scheme evidence collected for this course names a specific, confirmed WME01 instance of bod, awrt, a standalone dp/sf tag, or an indep tag in isolation — those gaps are recorded in §1 rather than closed with an invented example. This document also does not repeat the full mechanism, worked numbers, or trap taxonomy behind any entry above where a fuller lesson or CODEX deep-dive already owns that material; each such entry names where that fuller treatment lives instead of restating it. If a future pass finds a primary-source instance closing one of the §1 gaps, or a further real conflated-term pair grounded in an examiner report this course has not yet mined, it belongs added to this same file rather than started as a second document.