How the Mechanical Comprehension Test works
The MCT asks about the physics you would meet in an introductory high school course and how it applies to real situations: gases and liquids and how they affect pressure, volume and velocity, how engines work, electricity, gears, where weight sits, and simple machines such as pulleys and levers.
Many questions come with a drawing of the machine or system, and ask which way something turns, how much force is needed or what happens to a pressure or a speed.
It is the shortest-timed of the three OAR tests, at a reported 15 minutes, so speed matters more here than anywhere else in the OAR. It is adaptive, with no going back and no changing answers, and it can end early once it has measured you.
How to answer MCT questions
Most questions rest on a handful of rules. Know them well enough to apply them in seconds:
- Gears: meshed gears turn in opposite directions, and the gear with more teeth turns more slowly. Speed times teeth is the same on both.
- Levers: weight times distance from the fulcrum is equal on both sides when the lever balances.
- Pulleys: the more rope segments hold up the moving pulley, the less force you need and the more rope you pull.
- Fluids: in a pipe, water speeds up where the pipe narrows, and pressure in a still liquid grows with depth.
- Electricity: in series the same current flows through every part; in parallel each branch gets the full voltage.
- Look at the drawing before you read the options, and work out the direction or size of the answer first.
Worked example
A lever question: “A 120-pound load sits 2 feet from the fulcrum of a lever. How much force applied 6 feet from the fulcrum on the other side will balance it?” The options are (A) 40 lb, (B) 60 lb and (C) 360 lb.
Balance means the same weight times distance on each side: 120 × 2 = 240, and 240 ÷ 6 = 40 pounds, option A. Option C multiplies instead of dividing, which would mean the longer arm makes the job harder.
A fluids question: “Water flows through a pipe that narrows from 4 inches across to 2 inches. In the narrow section the water flows (A) faster, (B) slower, (C) at the same speed.” The same amount of water has to pass every point each second, so where the pipe is narrower it must move faster: A.
Tips for the real MCT
- Keep to about 30 seconds a question. If you are stuck, choose the option that fits the rule you know and move on.
- Do not leave questions unreached, and do not guess blindly as time runs out; both lower your score.
- Revise gears, levers, pulleys and fluids first. They come up most and are quickest to learn.
- Work out the direction of an effect before its size: knowing whether something goes up or down often rules out options straight away.
Practise the Mechanical Comprehension Test on CogniPrep
Our MCT gives you up to 30 adaptive questions in 15 minutes, three options each, mixing drawn gear, lever, pulley and circuit problems with questions on liquids and gases, engines and electricity. It never lets you go back, can end early, and takes points off if time runs out with questions unreached. Your result is our estimate on the OAR’s 20 to 80 scale, not an official score.