Mechanical Aptitude Mechanical Aptitude Knowledge 3 — Questions and Answers
Question 1: Two gears mesh together. Gear A has 10 teeth and spins at 200 RPM. Gear B has 40 teeth. How fast does Gear B spin?
- 25 RPM
- 50 RPM (Correct answer)
- 100 RPM
- 800 RPM
Correct answer: 50 RPM
Speed ratio is inverse to tooth ratio: 200 × (10/40) = 50 RPM.
Question 2: A cam converts:
- Linear motion to rotational motion
- Rotational motion to linear/reciprocating motion (Correct answer)
- Electrical energy to mechanical energy
- High speed to low speed
Correct answer: Rotational motion to linear/reciprocating motion
A cam (rotating eccentric shape) pushes a follower up and down, converting rotation into reciprocating linear motion.
Question 3: Which type of stress occurs when a rope is being pulled from both ends?
- Compression
- Shear
- Tension (Correct answer)
- Torsion
Correct answer: Tension
Tension is the pulling or stretching force that acts along the length of an object.
Question 4: Water flows through a pipe that narrows from 4 inches to 2 inches in diameter. The water speed in the narrow section will:
- Decrease by half
- Stay the same
- Increase by four times (Correct answer)
- Increase by two times
Correct answer: Increase by four times
Flow continuity requires that speed increases by the ratio of areas; a halved diameter means 1/4 the area, so speed quadruples.
Question 5: A spring with a spring constant of 10 N/m is stretched 0.5 m. What force does it exert?
- 0.05 N
- 2 N
- 5 N (Correct answer)
- 20 N
Correct answer: 5 N
Hooke's Law: F = k × x = 10 × 0.5 = 5 N.
Question 6: Which type of bearing is best suited for handling heavy axial (thrust) loads?
- Needle bearing
- Deep groove ball bearing
- Tapered roller bearing (Correct answer)
- Plain sleeve bearing
Correct answer: Tapered roller bearing
Tapered roller bearings are specifically designed to handle both radial and heavy axial thrust loads.
Question 7: A V-belt drive is slipping under load. The most likely cause is:
- Belts are too tight
- Pulley diameter is too large
- Belts are too loose or worn (Correct answer)
- Shaft speed is too low
Correct answer: Belts are too loose or worn
Loose or worn V-belts lose their grip in the pulley groove, causing slippage under load.
Mechanical Aptitude Mechanical Aptitude Knowledge 3
Two gears mesh together.
Gear A has 10 teeth and spins at 200 RPM.
Gear B has 40 teeth.
How fast does Gear B spin?