FCTC Pulleys, Gears, and Levers 5 — Questions and Answers
Question 1: A pulley system requires a worker to pull 12 feet of rope to raise a load 3 feet. What is the mechanical advantage of the system?
- 3
- 4 (Correct answer)
- 6
- 12
Correct answer: 4
Mechanical advantage = rope pulled ÷ load distance = 12 ÷ 3 = 4.
Question 2: A nutcracker is an example of which class of lever?
- First-class
- Second-class (Correct answer)
- Third-class
- It is not a lever
Correct answer: Second-class
A nutcracker is a second-class lever — the fulcrum is at the hinge end, effort is at the handles, and the nut (load) is in the middle.
Question 3: In a gear train, which gear arrangement is used to convert rotational motion into linear (straight-line) motion?
- Spur gears
- Bevel gears
- Rack and pinion (Correct answer)
- Worm gears
Correct answer: Rack and pinion
A rack and pinion system converts the rotational motion of a circular gear (pinion) into the linear motion of a flat toothed bar (rack).
Question 4: If friction is present in a pulley system, how does it affect the actual mechanical advantage compared to the theoretical value?
- Actual MA is higher than theoretical
- Actual MA is lower than theoretical (Correct answer)
- Friction has no effect on MA
- Actual MA equals theoretical MA
Correct answer: Actual MA is lower than theoretical
Friction reduces the actual mechanical advantage because some input force is lost overcoming friction, meaning more effort is needed than theory predicts.
Question 5: A lever has a load of 300 lbs placed 2 feet from the fulcrum. How far from the fulcrum must a 100-lb effort be applied to balance the lever?
- 2 feet
- 4 feet
- 6 feet (Correct answer)
- 8 feet
Correct answer: 6 feet
Using the lever principle: Load × Load arm = Effort × Effort arm → 300 × 2 = 100 × x → x = 6 feet.
Question 6: Which pulley arrangement provides NO mechanical advantage but is still useful in practical applications?
- Movable pulley
- Fixed pulley (Correct answer)
- Compound pulley
- Block and tackle
Correct answer: Fixed pulley
A single fixed pulley has a mechanical advantage of 1 (no force reduction) but changes the direction of force, which is practically useful.
Question 7: In a gear train where the driver has 30 teeth and the driven gear has 15 teeth, the output shaft rotates at what speed relative to the input?
- Half the input speed
- Twice the input speed (Correct answer)
- Same as the input speed
- Four times the input speed
Correct answer: Twice the input speed
Gear ratio = driver teeth / driven teeth = 30/15 = 2, so the driven gear spins twice as fast as the driver.
FCTC Pulleys, Gears, and Levers 5
A pulley system requires a worker to pull 12 feet of rope to raise a load 3 feet.
What is the mechanical advantage of the system?