ASVAB Mechanical Comprehension Practice Test 5

Question 1 easy

Gear A contains 16 teeth, and Gear B has 8 teeth. If Gear A rotates 15 full turns, how many full turns does Gear B complete?

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Correct answer: A — 30

The gear ratio is calculated by comparing the number of teeth: Gear A / Gear B = $$\frac{16}{8} = 2$$. Since Gear B is smaller, it rotates twice as fast as Gear A. Therefore, $$15\text{ turns} \times 2 = 30$$ full turns.

Question 2 easy

When a worker uses a longer, less steep ramp to push a heavy crate into a delivery truck rather than lifting it directly, how does this mechanical advantage affect the effort required?

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Correct answer: A — It reduces the required effort force, but increases the distance over which the force must be applied.

Simple machines like inclined planes provide mechanical advantage by reducing the effort force required to move a load, but they require applying that smaller force over a longer distance (Trade-off principle: Work = Force × Distance).

Question 3 easy

An inclined loading ramp at a warehouse is built with a mechanical advantage of 8. If a warehouse worker needs to move a cargo container weighing 400 newtons up the ramp, what is the minimum effort force required?

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Correct answer: A — 50 newtons

Mechanical Advantage (MA) = Load / Effort. Rearranging the formula to solve for effort force: Effort = Load / MA = $$400\text{ newtons} / 8 = 50$$ newtons.

Question 4 medium

Alex and Ben weigh 90 and 60 pounds respectively, and are both seated on the left side of a seesaw. Alex is seated 4 feet from the fulcrum, and Ben is seated 6 feet from the fulcrum. If their sister Clara weighs 120 pounds, at what distance from the fulcrum must she sit on the right side to achieve balance?

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Correct answer: A — 6 feet

To achieve balance, total torque on the left must equal total torque on the right. Left Torque = (90 lb × 4 ft) + (60 lb × 6 ft) = $$360 + 360 = 720$$ lb-ft. Right Torque = Clara's Weight × Distance = 120 lb × Distance. Solving for Distance: $$\frac{720}{120} = 6$$ feet.

Question 5 medium

A rescue team uses a block and tackle pulley system to lift an 840-pound generator up to a service platform 25 feet high. If the operator exerts an effort force of 70 pounds on the rope to lift the generator, what is the actual mechanical advantage of this setup?

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Correct answer: A — 12

Actual Mechanical Advantage (MA) = Load / Effort Force = 840 pounds / 70 pounds = 12. The height of 25 feet is extra information not needed to calculate the mechanical advantage.

Question 6 hard

A lever system is set up to lift a heavy crate. The distance from the fulcrum to the effort force is 14 feet, while the distance from the fulcrum to the load is 18 feet. If the crate exerts a downward weight of 210 pounds, what is the exact effort force required to lift the load?

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Correct answer: C — 270 pounds

Using the law of the lever (Effort Force × Effort Arm = Load Force × Load Arm): Effort × 14 ft = 210 lb × 18 ft. $$\text{Effort} \times 14 = 3780$$ lb·ft. Effort $$= \frac{3780}{14} = 270$$ pounds.

Question 7 medium

A delivery ramp is 12 feet long and raises cargo to a loading dock height of 4 feet. How much force is required to push a 360-pound equipment container up this ramp, assuming frictionless conditions?

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Correct answer: A — 120 pounds

The mechanical advantage (MA) of an inclined plane is Length / Height = 12 ft / 4 ft = 3. The required effort force = Load Weight / MA = $$360\text{ pounds} / 3 = 120$$ pounds.

Question 8 medium

Two workers are pulling a heavy crate across a floor using ropes. Worker A pulls to the left with a force of 45 newtons, while Worker B pulls to the right with a force of 62 newtons. What is the magnitude and direction of the net force acting on the crate?

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Correct answer: D — 17 newtons to the right

Forces acting in opposite directions are subtracted: 62 newtons (right) - 45 newtons (left) = 17 newtons. The resulting net force acts in the direction of the larger force, which is to the right.

Question 9 hard

Three identical structural beams—one made of structural steel, one made of aluminum, and one made of oak wood—have the same dimensions (12 feet long, 4 inches wide, 6 inches deep) and are supported at both ends. When an equal weight of 500 pounds is placed at the exact center of each beam, which beam will experience the LEAST amount of deflection (bending)?

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Correct answer: C — The steel beam, because steel has the highest Modulus of Elasticity (stiffness).

Deflection under a point load depends on the material's Modulus of Elasticity (Young's Modulus, E). Structural steel has a significantly higher E value (~200 GPa) compared to aluminum (~69 GPa) and oak (~11 GPa), making steel the stiffest material with the least deflection.

Question 10 hard

A warehouse team needs to elevate a 400-pound drum onto a 5-foot-high platform using one of two ramps: Ramp A is 10 feet long, and Ramp B is 20 feet long. Assuming friction is negligible, which statement accurately compares the effort force and total work required for both ramps?

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Correct answer: B — Ramp B requires half as much effort force as Ramp A, but both ramps require the same total work.

Ramp B is twice as long as Ramp A, doubling the mechanical advantage ($$\text{MA}_B = \frac{20}{5} = 4$$ vs $$\text{MA}_A = \frac{10}{5} = 2$$) and reducing the effort force by half. However, total work done (Work = Force × Distance = Weight × Height) depends only on the weight lifted and vertical height, so total work is identical for both ramps.

Question 11 hard

Two mechanics, Sam and Chris, are lifting identical 500-pound engine blocks onto a storage shelf that is 6 feet above the workshop floor. Sam uses a 3-pulley block-and-tackle system, while Chris uses a hydraulic crane. Assuming ideal mechanical conditions, which statement correctly describes the work done by Sam compared to Chris?

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Correct answer: B — Sam performs the exact same amount of work as Chris.

Work is defined as Force multiplied by Distance $$(W = F \times d)$$, which equals the change in gravitational potential energy $$(W = m \times g \times h)$$. Because both mechanics lift identical loads (500 lbs) to the same vertical height (6 ft), the total work done is identical (3,000 ft-lbs) regardless of the equipment used. Simple machines like pulleys or hydraulic systems reduce the required force but increase distance, keeping total work constant.