ASVAB 2025/2026 Advanced Mastery:
Mechanical Comprehension, Electronics, and
General Science Practice Questions
Subject: ASVAB 2025/2026 - Mechanical Comprehension & Technical
Proficiency
Question 1: A system consists of a compound pulley with a mechanical advantage of 4. If an
operator needs to lift a 200-pound load, and the system has an efficiency of 80%, what is the
actual force required to lift the load?
A) 50 pounds
B) 62.5 pounds
C) 80 pounds
D) 160 pounds
Correct Answer: B) 62.5 pounds
Explanation: Mechanical advantage is the ratio of output force to input force. With a mechanical
advantage of 4, the ideal input force is 50 lbs (). However, efficiency (E) is the ratio of
ideal work to actual work. Since the system is only 80% efficient, we calculate the required input
force as Ideal Force / Efficiency = .80 = 62.5 lbs. Distractors like 50 lbs ignore
friction/efficiency, while 80 and 160 pounds misapply the inverse efficiency constant.
Question 2: In a hydraulic system, if the piston on the input side has a surface area of 2 square
inches and the piston on the output side has a surface area of 10 square inches, what is the
theoretical output force if an input force of 50 pounds is applied?
A) 100 pounds
B) 200 pounds
C) 250 pounds
D) 500 pounds
Correct Answer: C) 250 pounds
Explanation: Hydraulic systems operate on Pascal’s Principle, where pressure is constant
throughout a closed system. Pressure (P) = Force (F) / Area (A). Input pressure = 50 lbs / 2 sq
,in = 25 psi. Since pressure is equal, Output Force = Pressure × Output Area = 25 psi × 10 sq in
= 250 lbs. The mechanical advantage here is the ratio of areas (10/2 = 5). 50 lbs × 5 = 250 lbs.
Question 3: A gear train consists of an input gear with 12 teeth driving an intermediate gear with
24 teeth, which then drives an output gear with 36 teeth. What is the total gear ratio of the
system?
A) 1:2
B) 1:3
C) 2:3
D) 3:1
Correct Answer: B) 1:3
Explanation: In a simple gear train, the intermediate gear acts as an idler gear, which changes
the direction of rotation but does not affect the overall gear ratio. The gear ratio is determined
by the ratio of the number of teeth on the final output gear to the number of teeth on the input
gear ( = 3). Thus, the ratio is 1:3. The intermediate gear is mathematically irrelevant to
the speed reduction calculation.
Question 4: If a circuit contains two 10-ohm resistors connected in parallel, and this combination
is connected in series with a 5-ohm resistor, what is the total equivalent resistance of the circuit?
A) 25 ohms
B) 15 ohms
C) 10 ohms
D) 7.5 ohms
Correct Answer: C) 10 ohms
Explanation: First, calculate the parallel resistance: 1/R_parallel = 1/10 + 1/10 = 2/10 = 1/5,
so R_parallel = 5 ohms. Next, add this in series with the 5-ohm resistor: Total Resistance = 5
ohms + 5 ohms = 10 ohms. Incorrect answers often incorrectly sum all components (25) or
incorrectly apply the parallel formula.
Question 5: A lever is 6 feet long. The fulcrum is placed 2 feet from the load. If a 100-pound
load is placed on the short end, what force must be applied to the long end (4 feet from the
fulcrum) to lift it?
A) 25 pounds
,B) 50 pounds
C) 75 pounds
D) 100 pounds
Correct Answer: B) 50 pounds
Explanation: Use the lever principle: Force1 × Distance1 = Force2 × Distance2. Here, (100 lbs
× 2 ft) = (X lbs × 4 ft). 200 = 4X, so X = 50 lbs. This is a Class 1 lever. The load is on the short
arm, so the effort arm (the long end) provides mechanical advantage, requiring less force than
the weight of the load.
Question 6: Which of the following describes the function of a zener diode in an electronic
circuit?
A) It rectifies alternating current to direct current.
B) It maintains a constant voltage across its terminals.
C) It amplifies weak electronic signals.
D) It converts light energy into electrical energy.
Correct Answer: B) It maintains a constant voltage across its terminals.
Explanation: Zener diodes are specifically designed to operate in the reverse breakdown region,
allowing them to maintain a stable, constant voltage (Zener voltage) across the device, making
them ideal for voltage regulation. Option A describes a standard rectifier diode, and Option C
describes a transistor.
Question 7: A pendulum clock is taken from a location at sea level to the top of a high mountain.
What happens to the period of the pendulum?
A) It decreases, and the clock runs fast.
B) It increases, and the clock runs slow.
C) It stays the same, as mass is independent of gravity.
D) It increases, and the clock runs fast.
Correct Answer: B) It increases, and the clock runs slow.
, Explanation: The period of a pendulum is given by $T = 2\pi \sqrt{\frac{L}{g}}$. On a mountain,
the acceleration due to gravity (g) is lower than at sea level. As g decreases, the period T
increases. A longer period means each swing takes more time, causing the clock to run slow.
Question 8: If a gas is compressed adiabatically (no heat exchange), what happens to the internal
energy of the gas?
A) It remains constant because no heat is added.
B) It increases as work is done on the gas.
C) It decreases as the volume decreases.
D) It increases because the temperature drops.
Correct Answer: B) It increases as work is done on the gas.
Explanation: According to the First Law of Thermodynamics, $\Delta U = Q - W$. For an
adiabatic process, Q = 0. When gas is compressed, work (W) is done on the gas, making W
negative in this convention. Therefore, $\Delta U = -(-W) = W$, meaning internal energy
increases, resulting in a temperature rise.
Question 9: In a DC motor, what is the purpose of the commutator?
A) To increase the voltage supplied to the motor.
B) To reverse the direction of current flow in the armature coil to maintain continuous rotation.
C) To convert mechanical energy into electrical energy.
D) To prevent the motor from overheating.
Correct Answer: B) To reverse the direction of current flow in the armature coil to maintain
continuous rotation.
Explanation: As the armature rotates in a magnetic field, the torque direction would reverse
every half-turn without the commutator. The commutator acts as a mechanical switch, reversing
the current direction at the appropriate time to ensure the torque remains in the same direction.
Question 10: A 12V battery is connected to a circuit with a total resistance of 3 ohms. If the
internal resistance of the battery is 1 ohm, what is the terminal voltage delivered to the external
circuit?
A) 6V
B) 8V
Mechanical Comprehension, Electronics, and
General Science Practice Questions
Subject: ASVAB 2025/2026 - Mechanical Comprehension & Technical
Proficiency
Question 1: A system consists of a compound pulley with a mechanical advantage of 4. If an
operator needs to lift a 200-pound load, and the system has an efficiency of 80%, what is the
actual force required to lift the load?
A) 50 pounds
B) 62.5 pounds
C) 80 pounds
D) 160 pounds
Correct Answer: B) 62.5 pounds
Explanation: Mechanical advantage is the ratio of output force to input force. With a mechanical
advantage of 4, the ideal input force is 50 lbs (). However, efficiency (E) is the ratio of
ideal work to actual work. Since the system is only 80% efficient, we calculate the required input
force as Ideal Force / Efficiency = .80 = 62.5 lbs. Distractors like 50 lbs ignore
friction/efficiency, while 80 and 160 pounds misapply the inverse efficiency constant.
Question 2: In a hydraulic system, if the piston on the input side has a surface area of 2 square
inches and the piston on the output side has a surface area of 10 square inches, what is the
theoretical output force if an input force of 50 pounds is applied?
A) 100 pounds
B) 200 pounds
C) 250 pounds
D) 500 pounds
Correct Answer: C) 250 pounds
Explanation: Hydraulic systems operate on Pascal’s Principle, where pressure is constant
throughout a closed system. Pressure (P) = Force (F) / Area (A). Input pressure = 50 lbs / 2 sq
,in = 25 psi. Since pressure is equal, Output Force = Pressure × Output Area = 25 psi × 10 sq in
= 250 lbs. The mechanical advantage here is the ratio of areas (10/2 = 5). 50 lbs × 5 = 250 lbs.
Question 3: A gear train consists of an input gear with 12 teeth driving an intermediate gear with
24 teeth, which then drives an output gear with 36 teeth. What is the total gear ratio of the
system?
A) 1:2
B) 1:3
C) 2:3
D) 3:1
Correct Answer: B) 1:3
Explanation: In a simple gear train, the intermediate gear acts as an idler gear, which changes
the direction of rotation but does not affect the overall gear ratio. The gear ratio is determined
by the ratio of the number of teeth on the final output gear to the number of teeth on the input
gear ( = 3). Thus, the ratio is 1:3. The intermediate gear is mathematically irrelevant to
the speed reduction calculation.
Question 4: If a circuit contains two 10-ohm resistors connected in parallel, and this combination
is connected in series with a 5-ohm resistor, what is the total equivalent resistance of the circuit?
A) 25 ohms
B) 15 ohms
C) 10 ohms
D) 7.5 ohms
Correct Answer: C) 10 ohms
Explanation: First, calculate the parallel resistance: 1/R_parallel = 1/10 + 1/10 = 2/10 = 1/5,
so R_parallel = 5 ohms. Next, add this in series with the 5-ohm resistor: Total Resistance = 5
ohms + 5 ohms = 10 ohms. Incorrect answers often incorrectly sum all components (25) or
incorrectly apply the parallel formula.
Question 5: A lever is 6 feet long. The fulcrum is placed 2 feet from the load. If a 100-pound
load is placed on the short end, what force must be applied to the long end (4 feet from the
fulcrum) to lift it?
A) 25 pounds
,B) 50 pounds
C) 75 pounds
D) 100 pounds
Correct Answer: B) 50 pounds
Explanation: Use the lever principle: Force1 × Distance1 = Force2 × Distance2. Here, (100 lbs
× 2 ft) = (X lbs × 4 ft). 200 = 4X, so X = 50 lbs. This is a Class 1 lever. The load is on the short
arm, so the effort arm (the long end) provides mechanical advantage, requiring less force than
the weight of the load.
Question 6: Which of the following describes the function of a zener diode in an electronic
circuit?
A) It rectifies alternating current to direct current.
B) It maintains a constant voltage across its terminals.
C) It amplifies weak electronic signals.
D) It converts light energy into electrical energy.
Correct Answer: B) It maintains a constant voltage across its terminals.
Explanation: Zener diodes are specifically designed to operate in the reverse breakdown region,
allowing them to maintain a stable, constant voltage (Zener voltage) across the device, making
them ideal for voltage regulation. Option A describes a standard rectifier diode, and Option C
describes a transistor.
Question 7: A pendulum clock is taken from a location at sea level to the top of a high mountain.
What happens to the period of the pendulum?
A) It decreases, and the clock runs fast.
B) It increases, and the clock runs slow.
C) It stays the same, as mass is independent of gravity.
D) It increases, and the clock runs fast.
Correct Answer: B) It increases, and the clock runs slow.
, Explanation: The period of a pendulum is given by $T = 2\pi \sqrt{\frac{L}{g}}$. On a mountain,
the acceleration due to gravity (g) is lower than at sea level. As g decreases, the period T
increases. A longer period means each swing takes more time, causing the clock to run slow.
Question 8: If a gas is compressed adiabatically (no heat exchange), what happens to the internal
energy of the gas?
A) It remains constant because no heat is added.
B) It increases as work is done on the gas.
C) It decreases as the volume decreases.
D) It increases because the temperature drops.
Correct Answer: B) It increases as work is done on the gas.
Explanation: According to the First Law of Thermodynamics, $\Delta U = Q - W$. For an
adiabatic process, Q = 0. When gas is compressed, work (W) is done on the gas, making W
negative in this convention. Therefore, $\Delta U = -(-W) = W$, meaning internal energy
increases, resulting in a temperature rise.
Question 9: In a DC motor, what is the purpose of the commutator?
A) To increase the voltage supplied to the motor.
B) To reverse the direction of current flow in the armature coil to maintain continuous rotation.
C) To convert mechanical energy into electrical energy.
D) To prevent the motor from overheating.
Correct Answer: B) To reverse the direction of current flow in the armature coil to maintain
continuous rotation.
Explanation: As the armature rotates in a magnetic field, the torque direction would reverse
every half-turn without the commutator. The commutator acts as a mechanical switch, reversing
the current direction at the appropriate time to ensure the torque remains in the same direction.
Question 10: A 12V battery is connected to a circuit with a total resistance of 3 ohms. If the
internal resistance of the battery is 1 ohm, what is the terminal voltage delivered to the external
circuit?
A) 6V
B) 8V
