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Mechanical Comprehension (MC)

Mechanical Comprehension (MC) tests how well you understand physical forces, motion, and simple machines. It is not part of your AFQT score, but it feeds the line scores that qualify you for mechanical, technical, and combat-support jobs.

Practice questions

Original Mechanical Comprehension questions in the ASVAB style. Pick an answer for instant feedback and an explanation, then keep going in the app.

  1. A worker uses a crowbar as a lever to pry up a heavy crate. The tip under the crate sits 4 inches from the pivot point, while the worker pushes down on the other end 24 inches from the pivot. Ignoring friction, how much mechanical advantage does the crowbar provide?

    1. 2 times
    2. 4 times
    3. 6 times
    4. 24 times

    For a lever, mechanical advantage equals the effort arm divided by the load arm: 24 inches / 4 inches = 6. The effort force is multiplied 6 times at the load.

  2. Two people lift a load using a rope-and-pulley system that has 3 supporting rope segments holding the load. Ignoring friction and the weight of the rope, how does the pulling force compare to the weight of the load being lifted?

    1. The pulling force equals the full weight of the load
    2. The pulling force is one-third of the load's weight
    3. The pulling force is three times the load's weight
    4. The pulling force is one-half of the load's weight

    The mechanical advantage of a pulley system equals the number of rope segments supporting the load. With 3 supporting segments, the required pull is 1/3 of the load's weight (though 3 times the rope must be pulled).

  3. A small gear with 10 teeth drives a larger gear with 40 teeth. If the small gear turns at 200 revolutions per minute, how fast does the large gear turn?

    1. 50 revolutions per minute
    2. 200 revolutions per minute
    3. 400 revolutions per minute
    4. 800 revolutions per minute

    Gear speed is inversely proportional to the number of teeth. The large gear has 4 times as many teeth (40/10), so it turns 4 times slower: 200 / 4 = 50 rpm.

  4. A hydraulic lift has a small input piston with an area of 2 square inches and a large output piston with an area of 20 square inches. If a force of 50 pounds is applied to the small piston, how much force is produced at the large piston?

    1. 50 pounds
    2. 100 pounds
    3. 250 pounds
    4. 500 pounds

    Pressure is transmitted equally through the fluid (Pascal's principle). The pressure is 50 lb / 2 in^2 = 25 psi, and force at the large piston is 25 psi x 20 in^2 = 500 pounds.

  5. A person pushes a heavy box across a floor at a steady, constant speed. Which statement about the forces on the box is correct?

    1. The pushing force is greater than the friction force
    2. The pushing force equals the friction force
    3. The pushing force is less than the friction force
    4. There is no friction acting on the box

    Constant speed means zero acceleration, so the net force is zero. The forward push exactly balances the backward friction force.

  6. A ramp (inclined plane) is used to roll a barrel up to a platform. If the same platform height is reached using a longer ramp instead of a shorter one, what happens to the effort needed to push the barrel up (ignoring friction)?

    1. The longer ramp requires less effort force
    2. The longer ramp requires more effort force
    3. The effort force is the same for both ramps
    4. The longer ramp requires no effort at all

    A longer ramp to the same height has a gentler slope and greater mechanical advantage (length divided by height). Less force is needed, though it must be applied over a greater distance.

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What it measures

Mechanical Comprehension measures your grasp of basic physical principles: how forces act on objects, how motion and energy behave, and how simple machines multiply effort. You do not need to have taken physics. The questions reward intuition about the everyday mechanical world, backed by a handful of straightforward formulas.

MC is not one of the four AFQT subtests (Arithmetic Reasoning, Mathematics Knowledge, Word Knowledge, and Paragraph Comprehension), so it does not affect your AFQT score or your basic eligibility to enlist. Instead, MC feeds the line scores used to qualify for specific jobs, especially in mechanical maintenance, vehicle and aircraft repair, construction, artillery, and other hands-on fields. If you are aiming at one of those roles, a strong MC score can open doors that AR and MK alone will not.

What's on it

Topics and skills you'll see

  • Forces and equilibrium — pushes, pulls, tension, compression, and when objects stay balanced or start to move.
  • Levers and torque — first-, second-, and third-class levers, fulcrum placement, and the balance of force times distance.
  • Mechanical advantage — how machines trade force for distance to make work easier.
  • Pulleys and blocks — fixed versus movable pulleys and how added rope segments reduce required effort.
  • Gears and pulleys in motion — how gear size changes speed and direction of rotation.
  • Inclined planes, wedges, and screws — trading a longer path for less force.
  • Work, energy, and power — the relationship between force, distance, and time.
  • Friction — how surfaces resist motion and how it is reduced.
  • Fluid and air pressure — hydraulics, pressure in containers, and buoyancy.
  • Structural support — weight distribution across beams, columns, and load points.

How to study it

Anchor yourself with a few core relationships and use them everywhere. Memorize that work = force x distance and that for a lever in balance, force x distance on one side = force x distance on the other. Almost every torque, pulley, and gear question is a variation of these ideas. When a machine lets you use less force, it always makes you move that force through a greater distance in return.

Build physical intuition, not just formulas. Picture a heavier person sitting closer to the middle of a seesaw to balance a lighter person on the far end, or a longer wrench loosening a stubborn bolt more easily. For gears, remember a small gear driving a large gear turns it slower but with more force, and that meshed gears spin in opposite directions. For pulleys, count the rope segments actually supporting the load: more supporting strands means less force needed.

Common mistakes to avoid: do not assume a machine gives you something for nothing — reduced force always costs added distance or lost speed. Do not ignore the units in a problem or rush past a diagram; the picture usually contains the answer. Watch gear and pulley questions for direction of rotation, which is easy to reverse by accident. And do not overthink — MC questions favor the simple, common-sense answer over an exotic one.

Practice with diagram-based questions and, when you can, look at real hardware: bikes, door hinges, bottle jacks, and hand tools are working examples of the exact principles tested. A little hands-on observation cements the concepts faster than rereading definitions.

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