Mechanical Aptitude Mechanical Aptitude Ultimate 4 — Questions and Answers
Question 1: A lever has its fulcrum 1 foot from a 300 lb load and 3 feet from the effort point. How much effort is required to lift the load?
- 100 lbs (Correct answer)
- 300 lbs
- 900 lbs
- 150 lbs
Correct answer: 100 lbs
By the law of levers: Effort × 3 = 300 × 1, so Effort = 300/3 = 100 lbs.
Question 2: What is the function of a flywheel in an engine?
- To store rotational energy and smooth out power pulses (Correct answer)
- To increase engine compression
- To cool the engine by circulating air
- To regulate fuel flow to the cylinders
Correct answer: To store rotational energy and smooth out power pulses
A flywheel's mass and rotational inertia store energy during power strokes and release it during compression strokes, smoothing engine output.
Question 3: Which type of bearing is most suitable for heavy radial loads at low speeds?
- Roller bearing (Correct answer)
- Ball bearing
- Needle bearing
- Thrust bearing
Correct answer: Roller bearing
Roller bearings have line contact instead of point contact, distributing the load over a larger area and handling heavier radial loads.
Question 4: Air pressure in a sealed container is 30 PSI at 60°F. If the temperature rises to 120°F (in Rankine: 520R to 580R), what is the new pressure?
- 33.5 PSI (Correct answer)
- 60 PSI
- 15 PSI
- 30 PSI
Correct answer: 33.5 PSI
Using Gay-Lussac's Law (P1/T1 = P2/T2 in Rankine): P2 = 30 × (580/520) ≈ 33.5 PSI.
Question 5: A flat washer placed under a bolt head primarily serves to:
- Distribute the clamping load over a larger area (Correct answer)
- Increase the torque capacity of the bolt
- Lock the bolt against vibration
- Seal against fluid or gas leakage
Correct answer: Distribute the clamping load over a larger area
A flat washer spreads the bolt's clamping force over a wider surface area, preventing the bolt head from pulling through soft or thin materials.
Question 6: In a reciprocating piston engine, what converts the piston's linear motion into rotational motion?
- Crankshaft (Correct answer)
- Camshaft
- Flywheel
- Governor
Correct answer: Crankshaft
The crankshaft uses offset journals (throws) connected to connecting rods to convert the piston's up-and-down linear motion into rotation.
Question 7: A spring with a spring constant of 50 lb/in is compressed 3 inches. How much energy is stored in the spring?
- 225 in-lbs (Correct answer)
- 150 in-lbs
- 450 in-lbs
- 75 in-lbs
Correct answer: 225 in-lbs
Spring potential energy = ½ × k × x² = ½ × 50 × 3² = ½ × 50 × 9 = 225 in-lbs.
Mechanical Aptitude Mechanical Aptitude Ultimate 4
A lever has its fulcrum 1 foot from a 300 lb load and 3 feet from the effort point.
How much effort is required to lift the load?