FCTC Test Pulleys, Gears, and Levers Questions and Answers 5 — Questions and Answers
Question 1: A firefighter uses a Halligan bar as a lever to force open a door. Moving the fulcrum closer to the load will:
- Decrease the mechanical advantage
- Increase the mechanical advantage (Correct answer)
- Have no effect on mechanical advantage
- Increase the load distance only
Correct answer: Increase the mechanical advantage
Moving the fulcrum closer to the load lengthens the effort arm relative to the load arm, increasing mechanical advantage.
Question 2: Two gears mesh together: the driver has 20 teeth spinning at 100 RPM and the driven gear has 50 teeth. What is the speed of the driven gear?
- 20 RPM
- 40 RPM (Correct answer)
- 100 RPM
- 250 RPM
Correct answer: 40 RPM
Speed ratio = teeth of driver ÷ teeth of driven = 20/50, so driven gear speed = 100 × (20/50) = 40 RPM.
Question 3: A rope rescue team rigs a 2:1 pulley system. If they pull 10 feet of rope, how high does the victim rise?
- 2.5 feet
- 5 feet (Correct answer)
- 10 feet
- 20 feet
Correct answer: 5 feet
With a 2:1 system the load rises half the distance the rope is pulled: 10 ÷ 2 = 5 feet.
Question 4: Which class of lever always has a mechanical advantage less than 1?
- First class
- Second class
- Third class (Correct answer)
- Fourth class
Correct answer: Third class
Third-class levers always have the effort between the fulcrum and the load, resulting in a mechanical advantage less than 1 but greater speed and range.
Question 5: Two gears of equal size are meshed together. A drives B at 200 RPM. What speed does Gear B rotate at?
- 100 RPM
- 200 RPM (Correct answer)
- 400 RPM
- Depends on torque
Correct answer: 200 RPM
Gears with equal numbers of teeth have a 1:1 ratio, so Gear B rotates at the same 200 RPM as Gear A.
Question 6: A pulley is described as having 'friction losses.' This means that in practice the actual mechanical advantage will be:
- Higher than the theoretical value
- Equal to the theoretical value
- Lower than the theoretical value (Correct answer)
- Zero
Correct answer: Lower than the theoretical value
Friction in pulleys and ropes consumes some of the input force, so actual (practical) mechanical advantage is always less than the ideal theoretical value.
Question 7: A second-class lever has an effort arm of 8 feet and a load arm of 2 feet. The load is 300 lbs. How much effort is needed?
- 37.5 lbs
- 75 lbs (Correct answer)
- 150 lbs
- 300 lbs
Correct answer: 75 lbs
Effort = Load × (Load arm ÷ Effort arm) = 300 × (2 ÷ 8) = 75 lbs.
FCTC Test Pulleys, Gears, and Levers Questions and Answers 5
A firefighter uses a Halligan bar as a lever to force open a door.
Moving the fulcrum closer to the load will: