FCTC FCTC Test Applying Mechanical Reasoning Questions and Answers 5 — Questions and Answers
Question 1: A screw has 20 threads per inch. If you turn it 5 full rotations, how far does it advance into the material?
- 0.25 inches (Correct answer)
- 4 inches
- 100 inches
- 0.05 inches
Correct answer: 0.25 inches
Advance = rotations / threads per inch = 5 / 20 = 0.25 inches.
Question 2: Two shafts are connected by a chain and sprocket. The drive sprocket has 15 teeth and the driven sprocket has 45 teeth. The drive shaft turns at 600 RPM. What is the output RPM?
- 200 RPM (Correct answer)
- 1800 RPM
- 400 RPM
- 150 RPM
Correct answer: 200 RPM
Output RPM = input RPM × (drive teeth / driven teeth) = 600 × (15/45) = 200 RPM.
Question 3: What type of stress acts on a bolt that holds two plates being pulled apart?
- Tensile stress (Correct answer)
- Shear stress
- Compressive stress
- Torsional stress
Correct answer: Tensile stress
When plates are pulled apart, the bolt is stretched along its length, placing it under tensile stress.
Question 4: A pump impeller spins faster when its motor speed increases. What happens to the fluid pressure it generates?
- Pressure increases (Correct answer)
- Pressure decreases
- Pressure stays the same
- Pressure becomes negative
Correct answer: Pressure increases
Centrifugal pump pressure output increases with impeller speed; doubling the speed roughly quadruples the pressure.
Question 5: A steel rod is heated. Which dimension changes the most proportionally?
- All dimensions expand proportionally (Correct answer)
- Length increases most
- Diameter increases most
- Only surface area increases
Correct answer: All dimensions expand proportionally
Thermal expansion is isotropic in steel, meaning all dimensions expand by the same fractional amount.
Question 6: Which of the following materials has the highest thermal conductivity and is therefore best for a heat sink?
- Copper (Correct answer)
- Steel
- Rubber
- Wood
Correct answer: Copper
Copper has one of the highest thermal conductivities of common metals, making it ideal for rapidly transferring heat away from components.
Question 7: A 10-pound weight hangs from a rope that passes over a frictionless fixed pulley and connects to a scale on the other end. What does the scale read?
- 10 lbs (Correct answer)
- 5 lbs
- 20 lbs
- 0 lbs
Correct answer: 10 lbs
A single fixed pulley only changes the direction of force, not its magnitude, so the scale reads the full 10 lbs.
FCTC FCTC Test Applying Mechanical Reasoning Questions and Answers 5
A screw has 20 threads per inch.
If you turn it 5 full rotations, how far does it advance into the material?