OAR OAR Mechanical Comprehension: Simple Machines 3 — Questions and Answers
Question 1: A compound pulley system has 4 rope segments supporting the load. What is the mechanical advantage?
- 1
- 2
- 3
- 4 (Correct answer)
Correct answer: 4
In a compound pulley, the mechanical advantage equals the number of rope segments supporting the load.
Question 2: A third-class lever has the effort applied between the fulcrum and the load. What is a real-world example?
- Crowbar
- Wheelbarrow
- Fishing rod (Correct answer)
- Nutcracker
Correct answer: Fishing rod
A fishing rod is a third-class lever where the effort (hand) is between the fulcrum (grip end) and the load (fish).
Question 3: If a lever arm on the effort side is 4 times longer than the resistance side, the lever provides a mechanical advantage of:
- 0.25
- 1
- 2
- 4 (Correct answer)
Correct answer: 4
Mechanical advantage = effort arm length / resistance arm length = 4/1 = 4.
Question 4: Which simple machine is essentially a circular inclined plane wrapped around a cylinder?
- Pulley
- Wheel and axle
- Wedge
- Screw (Correct answer)
Correct answer: Screw
A screw is an inclined plane (ramp) wrapped helically around a cylinder.
Question 5: A movable pulley is attached to a load. Compared to no pulley, lifting the load requires:
- Twice the force over the same distance
- Half the force over twice the distance (Correct answer)
- The same force over half the distance
- Half the force over half the distance
Correct answer: Half the force over twice the distance
A movable pulley halves the required force but requires pulling the rope twice the distance the load travels.
Question 6: An axe blade is a type of which simple machine?
- Lever
- Screw
- Wedge (Correct answer)
- Inclined plane
Correct answer: Wedge
An axe blade is a wedge — a double inclined plane that converts downward force into splitting force.
Question 7: A bolt and nut system works because the nut acts as which simple machine?
- A lever
- A fixed pulley
- A wheel and axle
- A screw (Correct answer)
Correct answer: A screw
The nut traveling along the bolt threads is a screw mechanism converting rotational motion into linear clamping force.
OAR OAR Mechanical Comprehension: Simple Machines 3
A compound pulley system has 4 rope segments supporting the load.
What is the mechanical advantage?