ExxonMobil Test ExxonMobil Mechanical Aptitude 2 — Questions and Answers
Question 1: A pulley system uses 3 ropes supporting a load. If the load weighs 900 N, how much force is needed to lift it (ignoring friction)?
- 200 N
- 300 N (Correct answer)
- 450 N
- 600 N
Correct answer: 300 N
A 3-rope pulley system provides a mechanical advantage of 3; force = 900 ÷ 3 = 300 N.
Question 2: What happens to the boiling point of water when pressure is increased?
- It decreases
- It stays the same
- It increases (Correct answer)
- It becomes unpredictable
Correct answer: It increases
Higher pressure raises the boiling point of water, which is why pressure cookers cook food faster.
Question 3: In a centrifugal pump, what is cavitation?
- A buildup of scale on the impeller
- Formation and collapse of vapor bubbles causing damage (Correct answer)
- Excessive vibration due to imbalance
- Leakage through the mechanical seal
Correct answer: Formation and collapse of vapor bubbles causing damage
Cavitation occurs when local pressure drops below vapor pressure, forming bubbles that implode and damage the impeller.
Question 4: Which of the following best describes the function of a pressure relief valve?
- To maintain constant flow rate
- To prevent overpressure by releasing fluid when pressure exceeds a set point (Correct answer)
- To measure pressure in a pipeline
- To reduce pressure for downstream equipment
Correct answer: To prevent overpressure by releasing fluid when pressure exceeds a set point
A pressure relief valve opens automatically when system pressure exceeds a preset limit to protect equipment.
Question 5: A belt drives two pulleys. Pulley A has a diameter of 10 cm and rotates at 400 RPM. What is the RPM of Pulley B with a diameter of 20 cm?
- 100 RPM
- 200 RPM (Correct answer)
- 300 RPM
- 800 RPM
Correct answer: 200 RPM
Speed ratio = D_A/D_B = 10/20 = 0.5; Speed B = 400 × 0.5 = 200 RPM.
Question 6: What is the main advantage of a floating roof in a crude oil storage tank?
- It allows easier cleaning of the tank interior
- It reduces vapor space and minimizes evaporative losses (Correct answer)
- It increases the structural strength of the tank
- It prevents corrosion on the tank walls
Correct answer: It reduces vapor space and minimizes evaporative losses
A floating roof sits directly on the liquid surface, eliminating the vapor space where evaporative losses and fire hazards occur.
ExxonMobil Test ExxonMobil Mechanical Aptitude 2
A pulley system uses 3 ropes supporting a load.
If the load weighs 900 N, how much force is needed to lift it (ignoring friction)?