ASVAB ASVAB Mechanical Comprehension Principles 4 — Questions and Answers
Question 1: A hydraulic jack has an input piston with area 2 sq in and an output piston with area 20 sq in. If you apply 50 lbs of force to the input, what force is produced at the output?
- 100 lbs
- 250 lbs
- 500 lbs (Correct answer)
- 1000 lbs
Correct answer: 500 lbs
Pascal's law: output force = input force × (output area / input area) = 50 × (20/2) = 500 lbs.
Question 2: Which type of gear arrangement reverses the direction of rotation between the driver and driven gear?
- Worm gear
- Bevel gear
- Spur gear pair (external) (Correct answer)
- Planetary gear
Correct answer: Spur gear pair (external)
Two external spur gears meshed together rotate in opposite directions.
Question 3: A steel beam is supported at both ends and loaded in the center. Where does the maximum bending stress occur?
- At the support points
- At the center top and bottom surfaces (Correct answer)
- Uniformly throughout
- At the neutral axis
Correct answer: At the center top and bottom surfaces
Maximum bending stress occurs at the outermost fibers (top and bottom) at the point of maximum bending moment.
Question 4: A flywheel is used in an engine primarily to:
- Increase fuel efficiency
- Store rotational energy and smooth out power pulses (Correct answer)
- Reduce engine temperature
- Increase compression ratio
Correct answer: Store rotational energy and smooth out power pulses
A flywheel's rotational inertia stores energy during power strokes and releases it during non-power strokes, smoothing engine output.
Question 5: If a 10-foot ladder leans against a wall with its base 6 feet from the wall, how high up the wall does it reach?
- 6 feet
- 7 feet
- 8 feet (Correct answer)
- 9 feet
Correct answer: 8 feet
Using the Pythagorean theorem: height = √(10² - 6²) = √(100-36) = √64 = 8 feet.
Question 6: What happens to the pressure of a gas in a sealed container when the temperature increases (volume constant)?
- Pressure decreases
- Pressure stays the same
- Pressure increases (Correct answer)
- Volume increases instead
Correct answer: Pressure increases
Gay-Lussac's Law states that at constant volume, pressure is directly proportional to absolute temperature.
Question 7: A cam converts:
- Rotary motion to linear (reciprocating) motion (Correct answer)
- Linear motion to rotary motion
- Fast rotation to slow rotation
- Electrical energy to mechanical energy
Correct answer: Rotary motion to linear (reciprocating) motion
A cam is a rotating or sliding piece that converts rotary motion into linear reciprocating motion via a follower.
ASVAB ASVAB Mechanical Comprehension Principles 4
A hydraulic jack has an input piston with area 2 sq in and an output piston with area 20 sq in.
If you apply 50 lbs of force to the input, what force is produced at the output?