OAR Mechanical Reasoning Flashcards

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)

Answer: About 114 HP

HP = (Torque × RPM) / 5,252 = (200 × 3,000) / 5,252 ≈ 114 HP.

A fixed pulley system redirects force but offers no mechanical advantage. Adding a second movable pulley creates a system with a mechanical advantage of:

Answer: 2

A single movable pulley halves the required effort force, giving a mechanical advantage of 2.

Which material expands the MOST when heated to the same temperature increase?

Answer: Aluminum

Aluminum has a higher coefficient of thermal expansion than steel, concrete, or glass.

A ball is thrown horizontally from a cliff at 20 m/s. Ignoring air resistance, how does its horizontal velocity change as it falls?

Answer: It remains constant

Gravity acts only vertically, so horizontal velocity stays constant in the absence of air resistance.

A pipe joint is leaking because the threads are stripped. The BEST immediate repair approach is to:

Answer: Wrap Teflon tape over the threads and retighten

Teflon tape fills thread gaps and creates a pressure-resistant seal on threaded pipe fittings.

An electric motor draws 10 amperes at 120 volts. What is its power consumption?

Answer: 1,200 watts

Power = Voltage × Current = 120 V × 10 A = 1,200 watts.

Two objects of different masses are dropped simultaneously from the same height in a vacuum. Which lands first?

Answer: They land at the same time

In a vacuum, all objects accelerate equally under gravity regardless of mass (Galileo's principle).