The trap in Mechanical Comprehension is reaching for a formula when the question is really testing whether you understand how a machine behaves. Work the six problems below - each one is built on a different core principle. Pick an answer first, then open the solution.
Q1Levers: mechanical advantage
- A. 4 times
- B. 2 times
- C. One-quarter as much
- D. 5 times
Show the solution
A lever's mechanical advantage is the effort arm divided by the load arm: 4 ÷ 1 = 4. Your output force is four times your input force.
Answer: A. 4 times
The trade-off is distance: to raise the load a little, you push the long end a lot farther. Longer effort arm means more force but more movement - the golden rule of every simple machine is that you never get something for nothing.
Q2Pulleys: fixed versus movable
- A. 25 pounds
- B. 50 pounds
- C. 100 pounds
- D. 150 pounds
Show the solution
A single fixed pulley only changes the direction of your pull - it gives no mechanical advantage. You pull down with the full weight of the crate, 50 pounds, in order to lift it up.
Answer: B. 50 pounds
The 25-pound answer is the classic trap: people assume any pulley halves the load. To actually reduce effort you need a movable pulley or a block-and-tackle with multiple supporting rope segments. A lone fixed pulley just makes the direction more convenient.
Q3Gears: speed and direction
- A. Three times faster, in the same direction
- B. At the same speed, in the opposite direction
- C. Three times slower, in the opposite direction
- D. Three times faster, in the opposite direction
Show the solution
Two gears that mesh directly always spin in opposite directions. Because the large gear has three times as many teeth, it turns one-third as fast - three times slower - than the small driving gear.
Answer: C. Three times slower, in the opposite direction
Trade speed for turning force: the bigger, slower gear delivers more torque, while the smaller, faster gear delivers less. The ratio of teeth is the inverse of the ratio of speeds, and meshed gears never turn the same way.
Q4Pressure: force over area
- A. 5 psi
- B. 20 psi
- C. 105 psi
- D. 500 psi
Show the solution
Pressure is force spread over area: P = F ÷ A = 100 ÷ 5 = 20 pounds per square inch.
Answer: B. 20 psi
The distractors are the wrong operations: 500 is force times area and 105 is force plus area. This is the heart of hydraulics - the same fluid pressure pushing on a larger output piston produces a larger force, which is how a small effort lifts a car.
Q5Inclined planes: trading force for distance
- A. More force, over a shorter distance
- B. The same force, over the same distance
- C. More force, over a longer distance
- D. Less force, over a longer distance
Show the solution
A longer, gentler ramp lets you use less force, but you have to push the box over a greater distance to reach the same height. The total work - force times distance - comes out the same on both ramps.
Answer: D. Less force, over a longer distance
An inclined plane trades force for distance, exactly like a lever or a pulley system. That trade is the single idea behind every simple machine: reduce the force you need and you always increase the distance you move.
Q6Torque: balancing a seesaw
- A. 3 feet
- B. 4 feet
- C. 6 feet
- D. 8 feet
Show the solution
Balance means equal torque on each side, where torque is weight multiplied by distance from the pivot. The heavy side gives 60 × 4 = 240. The light side must match it, so its distance is 240 ÷ 40 = 6 feet.
Answer: C. 6 feet
The lighter child always sits farther out - that is why a small person can balance a larger one. Set the two weight-times-distance products equal and solve for the missing distance. These seesaw problems are among the most common in the whole section.
How to prepare for a principle-driven section
Look at what these six share: nearly every one comes back to a single rule - you never get something for nothing. A machine that cuts the force you need always makes you move something farther, and balance always means equal torque on both sides. Once those instincts are automatic, most Mechanical Comprehension questions answer themselves. Once you have found your weak spots here, work through the Mechanical Comprehension questions real learners miss most to see the exact points where real test-takers slip.
Ready for a full-length practice set?
These six are a taste. Our downloadable ASVAB practice pack gives you a full timed exam with worked explanations for every question - start with the free sample, then grab the complete pack when you're ready.
Prefer the complete set? The full ASVAB practice tests covering all nine subtests are on Udemy with 300 practice questions and visuals.