Free ASVAB Mechanical Comprehension Practice Test
9 Mechanical Comprehension (MC) practice questions, each with a worked explanation of the right answer.
Last updated May 2026
The ASVAB Mechanical Comprehension (MC) subtest covers simple machines, force, motion, pressure, mechanical advantage. On the computer-adaptive CAT-ASVAB it has 15 questions with about 22 minutes to answer. It is not an AFQT subtest, but it feeds the line scores that decide which jobs you qualify for. Work the 9 questions below, then read each explanation. Understanding why the answer is right is what raises your score.
Question 1· Mechanical Comprehension
Answer & explanation
Correct answer: B. 4 feet
Why: Lever balance requires equal torques on both sides of the fulcrum: W1 x D1 = W2 x D2. Plug in: 10 lb x 6 ft = 15 lb x D2, so 60 = 15 x D2, and D2 = 4 feet. Choice A (2 feet) divides 6 by 3 instead of using the torque equation. Choice C (6 feet) keeps the same distance and ignores that the heavier weight needs a shorter arm. Choice D (9 feet) puts the heavier weight farther out, which would unbalance the lever further since 15 lb x 9 ft = 135 lb-ft, more than double the 60 lb-ft on the other side.
Question 2· Mechanical Comprehension
Answer & explanation
Correct answer: B. 50 RPM
Why: Meshing gears conserve linear tooth speed, so RPM is inversely proportional to tooth count: RPM_large = RPM_small x (teeth_small / teeth_large) = 200 x (10/40) = 50 RPM. Choice A (25 RPM) divides by 8 instead of 4, doubling the reduction. Choice C (100 RPM) only halves the speed, applying a 2:1 ratio instead of the actual 4:1. Choice D (800 RPM) inverts the formula and multiplies 200 by 4, treating the large gear as the faster one when in fact the larger gear always turns slower than the smaller one it meshes with.
Question 3· Mechanical Comprehension
Answer & explanation
Correct answer: B. 50 pounds
Why: Newton's Second Law: if an object does not accelerate, the net force is zero. The crate is stationary, so static friction adjusts to exactly cancel the applied push. Friction = 50 pounds, opposite to the push. Choice A (0 pounds) ignores that something must be canceling the 50-pound push. Choice C (150 pounds) confuses friction with the difference between weight and applied force. Choice D (200 pounds) uses the full weight as the friction force, but weight acts vertically and is canceled by the normal force, not by horizontal friction. Static friction only equals what is needed to prevent motion, up to its maximum.
Question 4· Mechanical Comprehension
Answer & explanation
Correct answer: C. 4
Why: Mechanical advantage of a wheel-and-axle equals the wheel radius divided by the axle radius: MA = 12 / 3 = 4. The effort applied at the wheel's rim travels a larger circle, while the axle moves a smaller circle with greater force. Choice A (2) halves the correct ratio, possibly confusing radius with diameter on only one side. Choice B (3) uses the axle radius alone as the answer. Choice D (6) appears to add the radii (12 + 3) and halve them, or otherwise mix dimensions. Only the radius ratio gives the correct mechanical advantage.
Question 5· Mechanical Comprehension
Answer & explanation
Correct answer: C. It redirects the force without any mechanical advantage.
Why: A fixed pulley has only one rope segment supporting the load, so its mechanical advantage equals 1. Its only function is to change the direction of the applied force, not its magnitude. Choice A (reduces force by half) describes a single movable pulley, which has MA = 2. Choice B (multiplies by rope segments) describes a block-and-tackle with multiple supporting strands. Choice D (eliminates gravity) is physically impossible; pulleys redistribute or redirect force but never cancel weight. Only choice C correctly identifies that the load still requires a pulling force equal to its weight.
Question 6· Mechanical Comprehension
Answer & explanation
Correct answer: C. Placing the block on a smaller face so less area contacts the table
Why: Pressure equals force divided by contact area: P = F / A. With weight held constant, shrinking the area concentrates the same force onto fewer square inches and raises pressure. Choice A (tilting at 45 degrees) actually reduces the normal force on the table because part of the weight vector shifts off-axis, lowering pressure. Choice B (increasing surface area) spreads force over more area and decreases pressure, the opposite of what is asked. Choice D (moving the block) changes location only; both area and weight stay the same, so pressure is unchanged. Only reducing the contact face increases pressure.
Question 7· Mechanical Comprehension
Answer & explanation
Correct answer: B. 5 psi
Why: Pressure equals force divided by area: P = F / A = 10 lb / 2 in^2 = 5 psi. Pascal's principle states this pressure is transmitted equally to every part of the enclosed fluid. Choice A (2 psi) uses the area as the answer directly, ignoring the force. Choice C (12 psi) adds the force and area (10 + 2), which mixes incompatible units. Choice D (20 psi) multiplies force by area (10 x 2), inverting the formula. The pressure-versus-force distinction matters: pressure is what the fluid carries; force is what each piston exerts, and the two are connected by piston area.
Question 8· Mechanical Comprehension
Answer & explanation
Correct answer: C. Projectile motion
Why: Projectile motion describes any object launched with a horizontal velocity that is then acted on only by gravity. The horizontal speed stays constant while vertical speed grows under g, producing a parabolic path. Choice A (circular motion) requires a centripetal force pulling toward a center point, not a constant downward gravitational pull. Choice B (simple harmonic motion) describes oscillation about an equilibrium, like a pendulum or spring, not a one-way arc. Choice D (linear motion) requires a straight-line path, but the ball curves downward as it leaves the table, ruling out a straight trajectory.
Question 9· Mechanical Comprehension
Answer & explanation
Correct answer: C. Increase the mechanical advantage by reducing effort force
Why: Mechanical advantage of an inclined plane equals ramp length divided by ramp height: MA = L / h. Increasing L while keeping h fixed makes the ratio larger, so MA goes up and the required effort force goes down. Choice A (increase effort) reverses the trade-off; a longer ramp lowers effort, not raises it. Choice B (decrease MA) inverts the formula. Choice D (no effect) ignores that MA depends explicitly on the L/h ratio. Work in equals work out: a longer ramp spreads the same lifting work over more distance, so the force at each point drops.
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What's on the ASVAB Mechanical Comprehension subtest
Tests understanding of physical principles and simple machines. Think levers, pulleys, gears, and basic physics applied to real situations.
Common topics you'll see:
- Levers & fulcrums
- Pulleys & mechanical advantage
- Gears & gear ratios
- Force, work & energy
- Pressure & hydraulics
- Properties of materials
- Structural support & load distribution
- Fluid dynamics basics
- Thermodynamics basics
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FAQ
- How many free Mechanical Comprehension practice questions are here?
- This page has 9 free ASVAB Mechanical Comprehension questions, each with the correct answer and a full worked explanation. They're free to use with no account required.
- Does Mechanical Comprehension count toward my AFQT score?
- No. Mechanical Comprehension is not one of the four AFQT subtests, so it does not affect your AFQT/enlistment score. It does feed line scores that determine which military jobs you qualify for.
- What does the Mechanical Comprehension subtest cover?
- Tests understanding of physical principles and simple machines. Think levers, pulleys, gears, and basic physics applied to real situations. On the CAT-ASVAB it has 15 questions with about 22 minutes to answer them. Topics include: Simple machines, force, motion, pressure, mechanical advantage.
- Are these the same as the real ASVAB questions?
- No. These are original practice questions in the same multiple-choice format and topic coverage as the real ASVAB. The actual test is a secure exam, so no one publishes its live items. Practicing this format is solid prep, but the real ASVAB score comes only from a test-center sitting.
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