Mechanical Aptitude Mechanical Aptitude Ultimate 2 — Questions and Answers
Question 1: A hydraulic jack uses a small piston with an area of 2 sq in and a large piston with an area of 20 sq in. If you apply 50 lbs of force to the small piston, what force does the large piston exert?
- 500 lbs (Correct answer)
- 100 lbs
- 250 lbs
- 1000 lbs
Correct answer: 500 lbs
Pascal's law states that pressure is equal throughout, so force scales with the ratio of areas: 50 × (20/2) = 500 lbs.
Question 2: Which type of wrench provides the best grip on a rounded bolt head?
- Pipe wrench
- Open-end wrench
- Box-end wrench (Correct answer)
- Adjustable wrench
Correct answer: Box-end wrench
A box-end wrench fully surrounds the bolt head and contacts more points, reducing the chance of slipping on a rounded head.
Question 3: A conveyor belt runs over two pulleys: a drive pulley (diameter 12 in) and an idler pulley (diameter 6 in). If the drive pulley rotates at 100 RPM, how fast does the idler pulley rotate?
- 200 RPM (Correct answer)
- 50 RPM
- 100 RPM
- 150 RPM
Correct answer: 200 RPM
Belt speed is constant, so the smaller pulley must spin faster: 100 × (12/6) = 200 RPM.
Question 4: What is the primary purpose of a snap ring (circlip) in a mechanical assembly?
- To retain a shaft or component within a bore or on a shaft (Correct answer)
- To provide electrical grounding
- To reduce friction between rotating parts
- To seal against fluid leakage
Correct answer: To retain a shaft or component within a bore or on a shaft
Snap rings fit into grooves and act as shoulders to prevent axial movement of shafts or components.
Question 5: Water flows through a pipe that narrows from 4 inches in diameter to 2 inches in diameter. What happens to the water's velocity?
- It quadruples (Correct answer)
- It doubles
- It stays the same
- It halves
Correct answer: It quadruples
By continuity, flow rate is constant, and area decreases by a factor of 4 (π×1² vs π×2²), so velocity must increase by a factor of 4.
Question 6: A worm gear set has a worm with 2 threads and a worm wheel with 40 teeth. If the worm rotates at 1200 RPM, what is the output speed?
- 60 RPM (Correct answer)
- 30 RPM
- 120 RPM
- 600 RPM
Correct answer: 60 RPM
Gear ratio = worm wheel teeth / worm threads = 40/2 = 20:1, so output speed = 1200/20 = 60 RPM.
Question 7: Which material has the highest thermal conductivity and is best suited for heat sinks?
- Copper (Correct answer)
- Steel
- Plastic
- Glass
Correct answer: Copper
Copper has the highest thermal conductivity among common engineering metals (~400 W/m·K), making it ideal for heat dissipation.
Mechanical Aptitude Mechanical Aptitude Ultimate 2
A hydraulic jack uses a small piston with an area of 2 sq in and a large piston with an area of 20 sq in.
If you apply 50 lbs of force to the small piston, what force does the large piston exert?