FCTC Test Pulleys, Gears, and Levers 1 — Questions and Answers
Question 1: A movable pulley is used to lift a 240-lb load. Ignoring friction, how much force must be applied to the rope?
- 240 lb
- 120 lb (Correct answer)
- 60 lb
- 480 lb
Correct answer: 120 lb
A movable pulley provides a mechanical advantage of 2 because two rope segments support the load. The required effort is 240 ÷ 2 = 120 lb.
Question 2: Gear X has 20 teeth and Gear Y has 80 teeth. If Gear X rotates at 160 RPM, how fast does Gear Y rotate?
- 640 RPM
- 80 RPM
- 40 RPM (Correct answer)
- 20 RPM
Correct answer: 40 RPM
The speed ratio is inversely proportional to the number of teeth: (20 ÷ 80) × 160 = 40 RPM. The larger gear always turns more slowly than the smaller driver gear.
Question 3: A lever has an effort arm of 6 feet and a resistance arm of 2 feet. What is the mechanical advantage?
- 12
- 4
- 3 (Correct answer)
- 2
Correct answer: 3
Mechanical advantage of a lever = effort arm ÷ resistance arm = 6 ÷ 2 = 3. This means a 3:1 force multiplication is achieved.
Question 4: A block-and-tackle system applies 50 lbs of effort through 6 rope segments supporting the load. What is the maximum load that can be lifted, ignoring friction?
- 8 lb
- 56 lb
- 300 lb (Correct answer)
- 600 lb
Correct answer: 300 lb
The mechanical advantage equals the number of supporting rope segments (6), so the maximum load = 6 × 50 = 300 lb.
Question 5: Which of the following is an example of a third-class lever?
- Wheelbarrow
- Crowbar
- Fishing rod (Correct answer)
- Bottle opener
Correct answer: Fishing rod
A fishing rod is a third-class lever: the effort (hand gripping the rod) is applied between the fulcrum (the butt end) and the load (the fish). Third-class levers trade force for speed and range of motion.
Question 6: Two meshed gears have a gear ratio of 4:1 (driver to driven). If the driver gear produces 10 lb-ft of torque, what torque does the driven gear produce, ignoring friction?
- 2.5 lb-ft
- 10 lb-ft
- 14 lb-ft
- 40 lb-ft (Correct answer)
Correct answer: 40 lb-ft
When speed is reduced by a gear ratio of 4:1, torque is multiplied by the same ratio: 10 × 4 = 40 lb-ft. Speed and torque trade off proportionally in a gear pair.
FCTC Test Pulleys, Gears, and Levers 1
A movable pulley is used to lift a 240-lb load.
Ignoring friction, how much force must be applied to the rope?