Mechanical Aptitude Levers, Pulleys, and Gears Questions and Answers — Questions and Answers
Question 1: A wheelbarrow is an example of which class of lever?
- First-Class Lever
- Second-Class Lever (Correct answer)
- Third-Class Lever
- Fourth-Class Lever
Correct answer: Second-Class Lever
A wheelbarrow is a second-class lever because the load (the contents of the barrow) is located between the fulcrum (the wheel's axle) and the effort (the force applied to the handles).
Question 2: In a pulley system, if a 100 lb weight is supported by 4 rope segments, what is the ideal mechanical advantage?
- 2
- 8
- 4 (Correct answer)
- 1
Correct answer: 4
The ideal mechanical advantage of a pulley system is equal to the number of rope segments supporting the load. In this scenario, with 4 supporting ropes, the mechanical advantage is 4.
Question 3: If a large gear with 60 teeth drives a small gear with 20 teeth, and the large gear makes one full rotation, how many rotations will the small gear make?
- One-third of a rotation
- One rotation
- Three rotations (Correct answer)
- Six rotations
Correct answer: Three rotations
The gear ratio is calculated by dividing the number of teeth on the driven gear by the number of teeth on the driver gear. In this case, the ratio is 60/20 = 3. This means for every one rotation of the large gear, the small gear will rotate three times.
Question 4: Which of the following simple machines provides a mechanical advantage GREATER than 1 and changes the direction of the force?
- A single fixed pulley
- A single movable pulley
- A first-class lever with the fulcrum closer to the load (Correct answer)
- A third-class lever
Correct answer: A first-class lever with the fulcrum closer to the load
A first-class lever, where the fulcrum is between the effort and the load, can change the direction of force. If the effort arm (distance from effort to fulcrum) is longer than the load arm (distance from load to fulcrum), the mechanical advantage will be greater than 1.
Question 5: A mechanic uses a 2-foot long wrench to loosen a bolt. If the mechanic applies effort at the very end of the wrench and the fulcrum is the center of the bolt, what class of lever is being used?
- Second-Class Lever
- First-Class Lever (Correct answer)
- Third-Class Lever
- It is not a lever
Correct answer: First-Class Lever
This scenario describes a first-class lever. The fulcrum is the center of the bolt, the effort is applied at the end of the wrench handle, and the load (resistance) is the force needed to turn the bolt, located at the fulcrum. Since the fulcrum is between the effort and the load, it is a first-class lever.
Question 6: Two meshed gears are rotating. Gear A has 40 teeth and is rotating clockwise. Gear B has 20 teeth. What is the rotational direction and relative speed of Gear B?
- Clockwise, faster
- Counter-clockwise, slower
- Clockwise, slower
- Counter-clockwise, faster (Correct answer)
Correct answer: Counter-clockwise, faster
When two external gears are meshed, they rotate in opposite directions. Since Gear A is smaller (fewer teeth), Gear B will rotate faster. The speed ratio is the inverse of the tooth ratio (40/20 = 2), so Gear B rotates twice as fast as Gear A.
Mechanical Aptitude Levers, Pulleys, and Gears Questions and Answers
A wheelbarrow is an example of which class of lever?