Mechanical Aptitude Mechanical Aptitude Principles 3 — Questions and Answers
Question 1: A pulley system has one fixed and one movable pulley. How much force is needed to lift a 240 lb load?
- 240 lbs
- 120 lbs (Correct answer)
- 60 lbs
- 80 lbs
Correct answer: 120 lbs
A compound pulley with one movable pulley provides a mechanical advantage of 2, so force needed is 240/2 = 120 lbs.
Question 2: What is the primary purpose of a bearing in a rotating machine?
- Increase torque
- Reduce friction between moving parts (Correct answer)
- Convert speed to force
- Amplify vibration
Correct answer: Reduce friction between moving parts
Bearings reduce friction between the rotating shaft and stationary housing, improving efficiency and life.
Question 3: A spring with a constant of 50 N/m is compressed by 0.2 m. What force does it exert?
- 250 N
- 10 N (Correct answer)
- 0.25 N
- 100 N
Correct answer: 10 N
Hooke's Law: F = k × x = 50 × 0.2 = 10 N.
Question 4: Which of the following is an example of a third-class lever?
- Wheelbarrow
- Nutcracker
- Tweezers (Correct answer)
- Crowbar
Correct answer: Tweezers
In a third-class lever the effort is between the fulcrum and load; tweezers fit this description.
Question 5: Water flows through a pipe that narrows from 4 inches to 2 inches in diameter. What happens to the water's speed?
- It halves
- It doubles
- It quadruples (Correct answer)
- It stays the same
Correct answer: It quadruples
Area decreases by a factor of 4 (diameter halved), so velocity must quadruple to maintain flow rate (continuity equation).
Question 6: A ramp is 12 feet long and 3 feet tall. What is the mechanical advantage of the ramp?
- 3
- 4 (Correct answer)
- 9
- 36
Correct answer: 4
Mechanical advantage of an inclined plane = length / height = 12 / 3 = 4.
Question 7: Which fastener is designed to prevent loosening caused by vibration?
- Flat washer
- Standard hex nut
- Lock nut (Nyloc) (Correct answer)
- Machine screw
Correct answer: Lock nut (Nyloc)
A lock nut (Nyloc) uses a nylon insert to grip the bolt threads and resist vibration-induced loosening.
Mechanical Aptitude Mechanical Aptitude Principles 3
A pulley system has one fixed and one movable pulley.
How much force is needed to lift a 240 lb load?