FREE FCTC Test Mechanical Reasoning Principles Questions and Answers Flashcards

A wrench with a 12-inch handle requires 30 ft-lbs of torque to turn a bolt. If you switch to an 18-inch handle wrench, how much force is needed to produce the same torque?

Answer: 20 lbs

Torque = Force × Length; 30 ft-lbs ÷ 1.5 ft = 20 lbs of force needed with the longer handle.

Water flows through a pipe that narrows from 4 inches in diameter to 2 inches. How does the water's speed change at the narrower section?

Answer: It quadruples

Because the cross-sectional area decreases by a factor of 4 (area ∝ diameter²), the velocity must increase by a factor of 4 to maintain continuity.

A steel spring is compressed 3 inches by a 60-lb force. How much force is required to compress it 5 inches?

Answer: 100 lbs

Hooke's Law: k = 60 ÷ 3 = 20 lb/in; force at 5 in = 20 × 5 = 100 lbs.

Two gears mesh together. Gear A has 40 teeth and Gear B has 10 teeth. If Gear A turns at 100 RPM, what is Gear B's speed?

Answer: 400 RPM

Gear ratio = 40:10 = 4:1, so Gear B turns 4 times faster: 100 × 4 = 400 RPM.

A hydraulic jack has an input piston with a 2 sq-in area and an output piston with a 20 sq-in area. If you apply 50 lbs on the input, what load can the output lift?

Answer: 500 lbs

Pascal's Law: Output force = Input force × (Output area ÷ Input area) = 50 × (20 ÷ 2) = 500 lbs.

A ball rolls off a level table and falls to the floor. Which path best describes its trajectory?

Answer: Curved parabolic arc

The ball maintains horizontal velocity while gravity accelerates it downward, producing a parabolic trajectory.

Which material would best conduct heat away from an engine's cylinder head?

Answer: Aluminum

Aluminum has high thermal conductivity (~205 W/m·K), making it ideal for heat dissipation in engine components.