12 guides · Unit 4

Engineering topic guides

One guide for every topic the QCAA Engineering external exam can ask about, in the order you would revise it. The exam assesses Unit 4 only, and everything in these guides serves a Unit 4 dot point. Where a guide uses older or Unit 1 material, such as stress–strain diagrams, it says so.

Every guide has the same shape. It starts with what the exam asks, then teaches the content one idea at a time with the real QCAA questions and mark-by-mark solutions placed where they belong. Each one finishes with a game plan for the topic and practice questions with worked solutions. Every past question from 2020 to 2025 is mapped, and 2026 is the first exam on the revised syllabus.

For the last two months before the external

Engineering: External game plan

How to read any exam question and know which game plan to reach for.

Your progress

Tick skills off inside each guide. Your ticks are saved in this browser only.

Where to start if time is short

1Friction and the inclined plane. It is the largest topic on the paper, and three separate subject reports (2022, 2023 and 2025) flagged it as a common weak spot.
2The lever rule. It is one short calculation, worth 4 or 5 marks in five of the six papers from 2020 to 2025, and the formula book gives you nothing for it.
3The community-synthesis question. It has a stable structure, so you can prepare a template for it.
4Simple machines. They supplied 14 of the 60 multiple-choice questions from 2020 to 2025 (four of them shared with the energy guide), more than any other topic, and single marks like these are easy to lose without noticing.

Two topics are new to the external exam

Electrical circuits and heat treatment are new for 2026. Circuits has no past questions at all, and heat treatment has only an incidental mention in one multiple-choice question (2024 Question 2). You have to learn both from the syllabus dot points instead of by drilling papers.

They are not equally hard. Circuits has almost every formula supplied: $I_\text{total} = \frac{V}{R_1} + \frac{V}{R_2} + \dots$ is not printed, but it follows from $V = IR$. You can also check your numerical answers yourself. Heat treatment has nothing supplied and is entirely written recall. Do not leave either one to the end.