ASVAB Mechanical Comprehension 2 — Questions and Answers
Question 1: A hydraulic jack uses a small piston with area 2 sq in and a large piston with area 20 sq in. If you apply 50 lbs to the small piston, what force does the large piston exert?
- 50 lbs
- 250 lbs
- 500 lbs (Correct answer)
- 1000 lbs
Correct answer: 500 lbs
Pascal's law: force scales with area ratio, so 50 × (20/2) = 500 lbs.
Question 2: Which type of gear arrangement reverses the direction of rotation between the input and output shaft?
- Worm gear
- Bevel gear
- Two meshing spur gears (Correct answer)
- Planetary gear
Correct answer: Two meshing spur gears
Two meshing spur gears always rotate in opposite directions.
Question 3: A spring with a spring constant of 200 N/m is compressed 0.05 m. How much potential energy is stored?
- 0.05 J
- 0.25 J (Correct answer)
- 5 J
- 10 J
Correct answer: 0.25 J
Spring potential energy = ½kx² = ½ × 200 × 0.05² = 0.25 J.
Question 4: A solid steel cylinder and a hollow steel cylinder of the same outer diameter and length are both rolled down an incline. Which reaches the bottom first?
- The solid cylinder (Correct answer)
- The hollow cylinder
- They reach at the same time
- Depends on the incline angle
Correct answer: The solid cylinder
The solid cylinder has a lower moment of inertia relative to its mass, so it accelerates faster down the incline.
Question 5: What is the mechanical advantage of a single fixed pulley?
- 0
- 1 (Correct answer)
- 2
- Depends on the load
Correct answer: 1
A single fixed pulley only changes the direction of force and provides a mechanical advantage of 1.
Question 6: Water flows through a pipe that narrows from 4 inches in diameter to 2 inches in diameter. How does the water speed change?
- It stays the same
- It doubles
- It quadruples (Correct answer)
- It halves
Correct answer: It quadruples
By the continuity equation, halving the diameter reduces area by factor 4, so speed increases 4×.
Question 7: A torque wrench applies 30 ft-lbs of torque using a 1.5 ft handle. What force must be applied?
- 10 lbs
- 20 lbs (Correct answer)
- 30 lbs
- 45 lbs
Correct answer: 20 lbs
Torque = Force × Distance, so Force = 30 / 1.5 = 20 lbs.
ASVAB Mechanical Comprehension 2
A hydraulic jack uses a small piston with area 2 sq in and a large piston with area 20 sq in.
If you apply 50 lbs to the small piston, what force does the large piston exert?