Bennett Mechanical Test Pulleys and Levers 3 — Questions and Answers
Question 1: A pair of scissors is an example of which combination of simple machines?
- Two first-class levers (Correct answer)
- Two second-class levers
- A pulley and a lever
- Two third-class levers
Correct answer: Two first-class levers
Scissors combine two first-class levers pivoting around a central fulcrum.
Question 2: Which lever class always produces a mechanical advantage less than 1?
- Third-class lever (Correct answer)
- First-class lever
- Second-class lever
- Compound lever
Correct answer: Third-class lever
In a third-class lever the effort arm is shorter than the load arm, giving a mechanical advantage below 1 but more speed.
Question 3: Two pulleys are arranged so one is fixed and one is movable. What is the mechanical advantage?
- 2 (Correct answer)
- 1
- 3
- 4
Correct answer: 2
One fixed plus one movable pulley gives a mechanical advantage of 2 from two supporting rope segments.
Question 4: On a balanced seesaw, a 100 lb child sits 3 ft from the pivot. Where must a 60 lb child sit to balance it?
- 5 ft from the pivot (Correct answer)
- 3 ft from the pivot
- 1.8 ft from the pivot
- 10 ft from the pivot
Correct answer: 5 ft from the pivot
Balance requires equal moments: 100 × 3 = 300, so 300 ÷ 60 = 5 ft.
Question 5: A bottle opener that pivots against the cap edge is which class of lever?
- Second-class lever (Correct answer)
- First-class lever
- Third-class lever
- Inclined plane
Correct answer: Second-class lever
A bottle opener has the load (cap) between the fulcrum and the effort, making it a second-class lever.
Question 6: If you increase the length of the effort arm on a lever while keeping the load arm the same, the mechanical advantage will:
- Increase (Correct answer)
- Decrease
- Stay the same
- Drop to zero
Correct answer: Increase
A longer effort arm relative to the load arm increases mechanical advantage.
Question 7: In a block and tackle, what is the trade-off for gaining mechanical advantage?
- You must pull more rope length (Correct answer)
- You must apply more force
- The load moves faster
- Friction is eliminated
Correct answer: You must pull more rope length
Greater mechanical advantage in a block and tackle requires pulling proportionally more rope.
Bennett Mechanical Test Pulleys and Levers 3
A pair of scissors is an example of which combination of simple machines?