OAR OAR Mechanical Reasoning 3 — Questions and Answers
Question 1: A car engine produces 200 foot-pounds of torque at 3,000 RPM. What is the horsepower output? (1 HP = 5,252 ft-lb/min at 1 RPM)
- About 57 HP
- About 114 HP (Correct answer)
- About 171 HP
- About 228 HP
Correct answer: About 114 HP
HP = (Torque × RPM) / 5,252 = (200 × 3,000) / 5,252 ≈ 114 HP.
Question 2: A fixed pulley system redirects force but offers no mechanical advantage. Adding a second movable pulley creates a system with a mechanical advantage of:
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
A single movable pulley halves the required effort force, giving a mechanical advantage of 2.
Question 3: Which material expands the MOST when heated to the same temperature increase?
- Steel
- Concrete
- Aluminum (Correct answer)
- Glass
Correct answer: Aluminum
Aluminum has a higher coefficient of thermal expansion than steel, concrete, or glass.
Question 4: A ball is thrown horizontally from a cliff at 20 m/s. Ignoring air resistance, how does its horizontal velocity change as it falls?
- It increases due to gravity
- It decreases due to air drag
- It remains constant (Correct answer)
- It first increases then decreases
Correct answer: It remains constant
Gravity acts only vertically, so horizontal velocity stays constant in the absence of air resistance.
Question 5: A pipe joint is leaking because the threads are stripped. The BEST immediate repair approach is to:
- Wrap Teflon tape over the threads and retighten (Correct answer)
- Apply epoxy putty to seal the leak from outside
- Replace the entire pipe section
- Tighten the joint further with more torque
Correct answer: Wrap Teflon tape over the threads and retighten
Teflon tape fills thread gaps and creates a pressure-resistant seal on threaded pipe fittings.
Question 6: An electric motor draws 10 amperes at 120 volts. What is its power consumption?
- 12 watts
- 120 watts
- 1,200 watts (Correct answer)
- 12,000 watts
Correct answer: 1,200 watts
Power = Voltage × Current = 120 V × 10 A = 1,200 watts.
Question 7: Two objects of different masses are dropped simultaneously from the same height in a vacuum. Which lands first?
- The heavier object
- The lighter object
- They land at the same time (Correct answer)
- It depends on their shape
Correct answer: They land at the same time
In a vacuum, all objects accelerate equally under gravity regardless of mass (Galileo's principle).
OAR OAR Mechanical Reasoning 3
A car engine produces 200 foot-pounds of torque at 3,000 RPM.
What is the horsepower output? (1 HP = 5,252 ft-lb/min at 1 RPM)