FCTC FREE FCTC Test Mechanical Reasoning Principles Questions and Answers 3

Question 1

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?

Accepted Answer

20 lbs

Answer

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

Question 2

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?

Accepted Answer

It quadruples

Answer

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.

Question 3

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

Accepted Answer

100 lbs

Answer

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

Question 4

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?

Accepted Answer

400 RPM

Answer

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

Question 5

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?

Accepted Answer

500 lbs

Answer

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

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FCTC FREE FCTC Test Mechanical Reasoning Principles Questions and Answers 3