How the Mechanical Concepts test works
Every question shows a drawing of a mechanical situation, asks one thing about it and gives three answers, A, B and C. Usually the drawing compares two things, and the third answer is that they are equal, that both apply, or that neither does. One EEI example ends with the instruction “If both, mark C.”
The same 44 questions and 20 minutes appear in CAST, CAST-R, MASS, POSS and TECH, so it is the one subtest you will meet whichever battery your utility uses. That is just over 27 seconds a question. Most sittings are on paper, so you can leave a question and come back to it before time is called.
TVA lists what it covers: force, laws of motion, friction, pressure, energy and work, simple machines, mechanical advantage and gears. Expect belts, pulleys, levers, tanks and pipes, springs and simple switches as well.
How to answer a Mechanical Concepts question
Work through each drawing in this order:
- Read the question before the drawing, so you know which part of the picture matters.
- Name the principle in a word or two: gear ratio, lever arm, depth and pressure, belt crossing.
- Decide the answer before you read the options. Then check whether option C, the equal or both answer, fits better.
- If two things differ in a way the principle ignores, such as tank width for water pressure, the answer is often C.
- If you are unsure after 30 seconds, mark your best guess and move on. Nothing is deducted for a wrong answer.
Worked examples
Gears. Gear A has 12 teeth and meshes with gear B, which has 36. Which gear makes more turns per minute? A: gear A. B: gear B. C: both the same. Meshed gears pass the same number of teeth past the contact point, so gear A turns 36 ÷ 12 = 3 times for every turn of gear B. The answer is A.
Pressure. Two open tanks are filled with water to the same depth of 3 metres. Tank A is narrow and tank B is three times as wide. At the bottom of which tank is the water pressure greater? A: tank A. B: tank B. C: they are equal. Pressure in a still liquid depends on depth, not width, so the answer is C.
Tips for the real Mechanical Concepts test
- Learn the handful of rules that carry most questions: meshed gears turn opposite ways, a crossed belt reverses direction, the smaller of two linked wheels turns faster, a longer lever arm needs less force.
- Treat C as a real answer. It is right whenever the difference shown in the drawing does not matter.
- Keep to about 27 seconds a question. A question you stall on costs you two easier ones further on.
- Answer every question before time is called. There is no penalty for guessing.
- Use EEI’s free practice tests if your utility gives you access. TVA points its MASS and POSS candidates to them.
Practise Mechanical Concepts on CogniPrep
Our game is a full-length paper: 44 drawn questions with three answers each on a 20-minute clock. You can skip, go back and change any answer, and the last question opens a review grid that shows what is still blank before you hand in. Nothing is deducted for a wrong answer, and your score out of 100 is the share of all 44 you got right, with a percentile against other CogniPrep users. The questions are our own.