ASVAB Study GuideMechanical Comprehension Practice Test 1
Tap an answer to check it instantly and read the explanation. 11 questions: 3 easy, 4 medium and 4 hard.
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Question 1 easy
What is the process called when liquid water turns into water vapor due to heat from the sun or ambient surroundings?
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Correct answer: C — evaporation
Evaporation is the phase transition in which water changes from a liquid state into gas/vapor when thermal energy is absorbed.
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Question 2 easy
Two workers are carrying a heavy 80-pound wooden beam on their shoulders. Where must the beam's center of gravity rest between them so that each worker supports exactly 40 pounds?
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Correct answer: B — equidistant from both workers
Placing the load directly in the middle (equidistant) distributes torque and downward gravitational weight evenly to both supporting points.
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Question 3 easy
What inward-directed force keeps a stone tied to a string moving in a smooth circular path rather than flying off in a straight line?
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Correct answer: A — centripetal force
Centripetal force acts towards the center of rotation, constantly pulling the orbiting body away from its straight inertial path.
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Question 4 medium
If an object is suspended in place by two equal upward tension forces that exactly balance its downward weight, what is the net force acting on the object?
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Correct answer: D — zero
When all opposing forces sum to zero $$(\Sigma F = 0)$$, the object is in mechanical equilibrium, resulting in zero net acceleration.
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Question 5 medium
A heavy bowling ball and a light tennis ball roll toward each other at the exact same velocity. Assuming an elastic collision, what will happen to the motion of the tennis ball upon impact?
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Correct answer: B — it will rebound backward at a higher speed in the opposite direction
Because the bowling ball has significantly greater mass, its momentum dominates the collision, causing the lighter tennis ball to reverse direction at a higher velocity.
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Question 6 medium
A dock worker exerts a force of 120 newtons to push a crate across a warehouse floor for a distance of 4.5 meters. How much work is done on the crate?
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Correct answer: B — 540 joules
Work is calculated using the formula Work = Force x Distance. Multiplying $$120\text{ N} \times 4.5\text{ m}$$ equals 540 J.
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Question 7 medium
Which of the following statements correctly describes the operational relationship between input force and output force in an ideal simple machine?
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Correct answer: A — Output force is the force exerted by the machine on an object as a direct result of the input force applied to it.
Simple machines transfer and transform energy; an output force cannot exist without an initial input force applied to the mechanism.
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Question 8 hard
A hydraulic lift receives an input force of 40 newtons and generates an output force of 360 newtons to raise a small vehicle. What is the mechanical advantage of the lift?
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Correct answer: C — 9
Mechanical Advantage (MA) is calculated as MA = Output Force / Input Force. Here, $$\frac{360\text{ N}}{40\text{ N}} = 9$$
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Question 9 hard
An engineer uses an inclined ramp to slide a heavy generator weighing 800 newtons into a truck bed. If pushing the generator up the ramp requires a force of 160 newtons, what is the mechanical advantage of the ramp?
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Correct answer: D — 5
The output force is the weight being lifted (800 N) and the input force is the effort applied (160 N). MA = $$\frac{800}{160} = 5$$
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Question 10 hard
A mechanic uses a crowbar as a lever to pry open a stuck crate. She exerts an input force of 45 newtons on the handle, causing the crowbar to apply an output force of 315 newtons to the lid. What is the mechanical advantage of the crowbar?
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Correct answer: B — 7
Mechanical Advantage (MA) equals the output force divided by the input force: $$\frac{315\text{ N}}{45\text{ N}} = 7$$
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Question 11 hard
A compound machine combines a wheel and axle with a block-and-tackle pulley system containing 4 supporting strands. The radius of the wheel is 30 cm and the radius of the axle is 6 cm. If the machine operates at an overall mechanical efficiency of 80%, what minimum input force must be applied to the wheel rim to raise a 1,000-newton load?
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Correct answer: B — 62.5 newtons
First, calculate the Ideal Mechanical Advantage (IMA) of the wheel and axle: $$\text{IMA}_{\text{wheel}} = 30\text{ cm} / 6\text{ cm} = 5$$. Next, the pulley system provides an $$\text{IMA}_{\text{pulley}} = 4$$. The total IMA of the compound machine is $$5 \times 4 = 20$$. Accounting for the 80% efficiency, the Actual Mechanical Advantage (AMA) is $$20 \times 0.80 = 16$$. Finally, the required input force is calculated as Input Force = Load / AMA $$= \frac{1{,}000\text{ N}}{16} = 62.5\text{ N}$$