ASVAB Mechanical Comprehension Practice Test 7

Question 1 easy

Which physical property describes an object's resistance to a change in its state of motion?

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Correct answer: A — inertia

Inertia is the property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

Question 2 medium

A worker uses a lever to lift a heavy crate, applying force at a distance of 1.2 meters from the fulcrum. If the lever provides a mechanical advantage of 0.4, what is the length of the output arm?

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Correct answer: B — 3.0 meters

Mechanical advantage for a lever is calculated as the ratio of the input arm length to the output arm length (MA = Input Arm / Output Arm). Rearranging the formula gives Output Arm = Input Arm / MA = $$\frac{1.2}{0.4} = 3.0$$ meters.

Question 3 easy

What physical quantity is defined as the rate at which work is done over a period of time?

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Correct answer: A — power

Power is defined in physics as the amount of energy transferred or converted per unit time, which is exactly the rate at which work is done.

Question 4 medium

A gardener uses a pair of shears with an output arm measuring 0.45 meters. If the mechanical advantage of the shears is 0.6, what is the length of the input arm?

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Correct answer: C — 0.27 meters

For levers, Mechanical Advantage = Input Arm / Output Arm. By multiplying the mechanical advantage by the output arm, we find the input arm: $$0.6 \times 0.45 = 0.27$$ meters.

Question 5 easy

Sarah pushed against a solid brick wall with a force of 800 newtons for 5 minutes, but the wall did not budge. How much work did Sarah perform on the wall?

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Correct answer: B — 0 joules

Work is calculated as Force multiplied by Distance $$(W = F \times d)$$. Since the wall did not move, the distance is zero. Therefore, regardless of the force applied, the work done on the wall is 0 joules.

Question 6 easy

A forklift applies a steady force of 4,500 newtons to push a pallet of boxes across a warehouse floor for a distance of 40 meters. How much work is done by the forklift?

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Correct answer: A — 180,000 joules

Work is calculated by multiplying the force applied by the distance moved in the direction of the force. $$W = 4{,}500\text{ N} \times 40\text{ m} = 180{,}000$$ joules.

Question 7 medium

Two technicians work together to slide a heavy generator across a smooth warehouse floor. They apply a combined horizontal force of 650 newtons and perform 2,275 joules of work. What distance did they move the generator?

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Correct answer: C — 3.5 meters

Work is defined as Force multiplied by Distance (Work = Force × Distance). Rearranging the formula to solve for distance yields Distance = Work / Force = $$\frac{2{,}275\text{ J}}{650\text{ N}} = 3.5$$ meters.

Question 8 medium

Which of the following magnetic pole alignments will result in a force of attraction between two bar magnets?

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Correct answer: A — North pole facing South pole

The fundamental law of magnetism states that opposite poles attract each other (North attracts South), whereas like poles repel each other (North repels North, South repels South).

Question 9 hard

Under standard atmospheric conditions at 20°C (68°F) at sea level, what is the approximate speed of sound traveling through dry air?

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Correct answer: B — 343 meters per second (approx. 1,125 feet per second)

The speed of sound in dry air at 20°C (68°F) at sea level is approximately 343 meters per second (1,125 ft/s or 767 mph). It varies primarily with temperature and the medium through which it travels.

Question 10 hard

Two solid steel spheres, Sphere A with a mass of 10 kg and Sphere B with a mass of 2 kg, roll directly toward each other at identical speeds on a frictionless surface. Upon colliding elastically, what will happen to the larger sphere (Sphere A)?

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Correct answer: A — Sphere A will continue moving in its original direction, but at a reduced speed.

Because Sphere A has significantly greater mass and thus greater momentum $$(p = m \times v)$$ than Sphere B at equal speeds, the total momentum vector points in Sphere A's direction. In an elastic collision, Sphere A retains enough forward momentum to continue moving forward, while Sphere B is repelled backward.

Question 11 hard

When a motor vehicle applies its brakes to slow down while traveling along a straight highway, what physical term specifically defines its rate of decrease in velocity?

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Correct answer: D — Deceleration (Negative acceleration)

Deceleration refers to acceleration that opposes the current velocity vector, causing an object to decrease its speed over time. It is mathematically represented as negative acceleration.

Question 12 hard

When designing a high-speed elevator system, which fundamental physics concepts and mechanical principles must engineers account for to ensure safe operation?

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Correct answer: A — All of the above (Friction, acceleration, and momentum)

Designing complex mechanical movement systems like high-speed elevators or roller coasters requires integrating all core principles of dynamics: managing friction for braking, controlling acceleration for passenger safety, and accounting for momentum during movement and stopping.