FCTC Mechanical Reasoning Principles Questions and Answers 4 — Questions and Answers
Question 1: A lever 10 feet long has its fulcrum 2 feet from one end. A 200 lb load is placed at the short end. What force must be applied at the long end to balance it?
- 50 lbs (Correct answer)
- 100 lbs
- 40 lbs
- 25 lbs
Correct answer: 50 lbs
Torque balance: Load × short arm = Effort × long arm → 200 × 2 = Effort × 8, so Effort = 400/8 = 50 lbs.
Question 2: Which of the following would cause a V-belt drive to slip on its pulley?
- Insufficient belt tension (Correct answer)
- Too much belt tension
- A smaller drive pulley
- Higher ambient temperature
Correct answer: Insufficient belt tension
A V-belt requires adequate tension to generate the friction needed to transfer torque without slipping.
Question 3: An inclined plane is 12 feet long and rises 3 feet. What is its mechanical advantage?
- 4 (Correct answer)
- 3
- 36
- 0.25
Correct answer: 4
Mechanical advantage of an inclined plane = length / height = 12 / 3 = 4.
Question 4: Two gears are in mesh. Gear A has 20 teeth and rotates at 600 RPM. Gear B has 60 teeth. What is the speed of Gear B?
- 200 RPM (Correct answer)
- 1800 RPM
- 400 RPM
- 300 RPM
Correct answer: 200 RPM
Speed ratio = teeth of driver / teeth of driven = 20/60, so Gear B speed = 600 × (20/60) = 200 RPM.
Question 5: A pressure gauge on a boiler reads 150 PSI. If the boiler's safety valve is set to 175 PSI, what is the pressure margin before the valve opens?
- 25 PSI (Correct answer)
- 150 PSI
- 175 PSI
- 325 PSI
Correct answer: 25 PSI
Pressure margin = safety valve setting − current pressure = 175 − 150 = 25 PSI.
Question 6: A screw has 16 threads per inch. How far does it advance into a material with one full revolution?
- 1/16 inch (Correct answer)
- 1/8 inch
- 16 inches
- 1/4 inch
Correct answer: 1/16 inch
Pitch (advance per revolution) = 1 / threads per inch = 1/16 inch.
Question 7: When two springs with the same spring constant are connected in parallel, the combined spring constant is:
- Twice the individual spring constant (Correct answer)
- Half the individual spring constant
- Equal to one spring constant
- Four times the individual spring constant
Correct answer: Twice the individual spring constant
Springs in parallel add their constants: k_total = k₁ + k₂ = 2k for identical springs.
FCTC Mechanical Reasoning Principles Questions and Answers 4
A lever 10 feet long has its fulcrum 2 feet from one end.
A 200 lb load is placed at the short end.
What force must be applied at the long end to balance it?