Mechanical Aptitude Ultimate Flashcards

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?

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.

Which type of wrench provides the best grip on a rounded bolt head?

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.

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?

Answer: 200 RPM

Belt speed is constant, so the smaller pulley must spin faster: 100 × (12/6) = 200 RPM.

What is the primary purpose of a snap ring (circlip) in a mechanical assembly?

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.

Water flows through a pipe that narrows from 4 inches in diameter to 2 inches in diameter. What happens to the water's velocity?

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.

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?

Answer: 60 RPM

Gear ratio = worm wheel teeth / worm threads = 40/2 = 20:1, so output speed = 1200/20 = 60 RPM.

Which material has the highest thermal conductivity and is best suited for heat sinks?

Answer: Copper

Copper has the highest thermal conductivity among common engineering metals (~400 W/m·K), making it ideal for heat dissipation.