OAR OAR Mechanical Comprehension: Simple Machines 2 — Questions and Answers
Question 1: A wheel and axle consists of a large wheel attached to a smaller axle. If the wheel radius is 30 cm and the axle radius is 5 cm, what is the mechanical advantage?
- 3
- 6 (Correct answer)
- 10
- 15
Correct answer: 6
Mechanical advantage of a wheel and axle = wheel radius / axle radius = 30 / 5 = 6.
Question 2: A wedge is used to split a log. If you double the length of the wedge while keeping the same width, what happens to its mechanical advantage?
- It halves
- It stays the same
- It doubles (Correct answer)
- It quadruples
Correct answer: It doubles
Mechanical advantage of a wedge = length / width, so doubling the length doubles the mechanical advantage.
Question 3: Which class of lever has the fulcrum between the effort and the load?
- First class (Correct answer)
- Second class
- Third class
- Fourth class
Correct answer: First class
A first-class lever has the fulcrum positioned between the effort force and the load, like a seesaw.
Question 4: A screw with a pitch of 0.5 cm is turned with a screwdriver handle of radius 2 cm. What is the mechanical advantage (use π ≈ 3.14)?
- 12.56
- 25.12 (Correct answer)
- 6.28
- 4.00
Correct answer: 25.12
MA of a screw = 2π × radius / pitch = 2 × 3.14 × 2 / 0.5 = 25.12.
Question 5: In a fixed pulley system, what is the mechanical advantage?
- 0
- 1 (Correct answer)
- 2
- Depends on rope length
Correct answer: 1
A single fixed pulley has a mechanical advantage of 1 — it changes direction of force but does not multiply it.
Question 6: A ramp is 10 meters long and rises 2 meters high. How much force is needed to push a 500 N box up the ramp (ignoring friction)?
- 50 N
- 100 N (Correct answer)
- 250 N
- 500 N
Correct answer: 100 N
Force needed = weight × (height / length) = 500 × (2/10) = 100 N.
Question 7: Two gears mesh together. Gear A has 12 teeth and Gear B has 36 teeth. If Gear A turns at 90 rpm, how fast does Gear B turn?
- 270 rpm
- 90 rpm
- 45 rpm
- 30 rpm (Correct answer)
Correct answer: 30 rpm
Output speed = input speed × (teeth on A / teeth on B) = 90 × (12/36) = 30 rpm.
OAR OAR Mechanical Comprehension: Simple Machines 2
A wheel and axle consists of a large wheel attached to a smaller axle.
If the wheel radius is 30 cm and the axle radius is 5 cm, what is the mechanical advantage?