FCTC Applying Mechanical Reasoning 3 — Questions and Answers
Question 1: An inclined plane is 12 feet long and rises 3 feet. What is its mechanical advantage?
- 1
- 2
- 4 (Correct answer)
- 9
Correct answer: 4
Mechanical advantage of an inclined plane = length ÷ height = 12 ÷ 3 = 4.
Question 2: A wheel and axle has a wheel radius of 18 inches and an axle radius of 3 inches. What is its mechanical advantage?
- 3
- 6 (Correct answer)
- 15
- 54
Correct answer: 6
Mechanical advantage = wheel radius ÷ axle radius = 18 ÷ 3 = 6.
Question 3: Two pistons in a hydraulic system are connected. The smaller piston moves 10 inches downward. If the area ratio (large/small) is 5:1, how far does the large piston move?
- 0.5 in
- 2 in (Correct answer)
- 5 in
- 50 in
Correct answer: 2 in
Volume is conserved; with a 5:1 area ratio, the large piston moves 10 ÷ 5 = 2 inches.
Question 4: A pulley system is fixed to the ceiling (fixed pulley only). What does this arrangement provide?
- Doubles the force applied
- Changes the direction of force only (Correct answer)
- Quadruples the force applied
- Reduces force by half
Correct answer: Changes the direction of force only
A single fixed pulley only redirects the force — it provides no mechanical advantage, so you still lift with the same force as the load.
Question 5: Gear A (10 teeth) drives Gear B (30 teeth), which is on the same shaft as Gear C (10 teeth), which drives Gear D (30 teeth). What is the overall gear ratio from A to D?
- 3:1
- 6:1
- 9:1 (Correct answer)
- 12:1
Correct answer: 9:1
Each gear pair has a 3:1 ratio; combined in series they multiply: 3 × 3 = 9:1 overall ratio.
Question 6: A wrench handle is 12 inches long. To loosen a bolt, a mechanic applies 30 lb of force perpendicular to the handle. What torque is applied?
- 2.5 ft-lb
- 30 ft-lb (Correct answer)
- 42 ft-lb
- 360 ft-lb
Correct answer: 30 ft-lb
Torque = force × distance = 30 lb × 1 ft (12 in ÷ 12) = 30 ft-lb.
Question 7: What is the primary purpose of a flywheel in an engine?
- Increase fuel efficiency
- Store rotational energy to smooth out power strokes (Correct answer)
- Cool the engine block
- Reduce gear slippage
Correct answer: Store rotational energy to smooth out power strokes
A flywheel stores rotational kinetic energy during power strokes and releases it during non-power strokes to keep rotation smooth.
FCTC Applying Mechanical Reasoning 3
An inclined plane is 12 feet long and rises 3 feet.
What is its mechanical advantage?