Mechanical Aptitude Mechanical Aptitude Levers, Pulleys, and Gears 4 — Questions and Answers
Question 1: A first-class lever has the fulcrum exactly in the middle. What is its mechanical advantage?
- 0
- 0.5
- 1 (Correct answer)
- 2
Correct answer: 1
When the fulcrum is centered, the effort arm equals the resistance arm, giving a mechanical advantage of exactly 1.
Question 2: Helical gears are preferred over spur gears for high-speed applications primarily because they:
- Are cheaper to manufacture
- Engage more gradually, reducing noise and vibration (Correct answer)
- Spin in the same direction
- Have a higher gear ratio
Correct answer: Engage more gradually, reducing noise and vibration
Helical gears have angled teeth that engage progressively, spreading the load and reducing the noise and vibration common in spur gears.
Question 3: In a pulley system, if you pull 6 feet of rope to raise a load by 2 feet, what is the mechanical advantage?
- 0.33
- 2
- 3 (Correct answer)
- 12
Correct answer: 3
Mechanical advantage = distance effort moves ÷ distance load moves = 6 ÷ 2 = 3.
Question 4: A pair of scissors is an example of which lever class?
- First class (Correct answer)
- Second class
- Third class
- Compound lever
Correct answer: First class
Scissors are first-class levers because the fulcrum (pivot pin) is between the effort (finger handles) and the load (blades cutting material).
Question 5: A worm gear system provides a high gear ratio and:
- Is reversible — the output shaft can drive the input shaft
- Is typically non-reversible — the worm can drive the gear but not vice versa (Correct answer)
- Operates only at high speeds
- Works only with perpendicular shafts at the same height
Correct answer: Is typically non-reversible — the worm can drive the gear but not vice versa
Worm gears are self-locking in most configurations because the high friction prevents the wheel from backdriving the worm.
Question 6: If a lever requires 50 lbs of effort to lift a 200 lb load, what is its mechanical advantage?
- 0.25
- 2
- 4 (Correct answer)
- 10
Correct answer: 4
Mechanical advantage = Load ÷ Effort = 200 ÷ 50 = 4.
Question 7: Two meshing gears always rotate in:
- The same direction
- Opposite directions (Correct answer)
- Alternating directions
- The same direction at different speeds
Correct answer: Opposite directions
When two gears mesh directly, they rotate in opposite directions because their teeth push against each other.
Mechanical Aptitude Mechanical Aptitude Levers, Pulleys, and Gears 4
A first-class lever has the fulcrum exactly in the middle.
What is its mechanical advantage?