GCAT Mechanical Reasoning Concepts 4 — Questions and Answers
Question 1: A compound pulley system has 4 rope segments supporting a load. What is the ideal mechanical advantage?
- 1
- 2
- 4 (Correct answer)
- 8
Correct answer: 4
The mechanical advantage of a block-and-tackle equals the number of rope segments supporting the moving block.
Question 2: Which material property describes a material's ability to return to its original shape after a deforming force is removed?
- Plasticity
- Ductility
- Elasticity (Correct answer)
- Brittleness
Correct answer: Elasticity
Elasticity is the property by which a material recovers its original shape after deformation forces are removed.
Question 3: A flywheel stores kinetic energy in rotation. If its rotational speed doubles, its stored energy:
- Stays the same
- Doubles
- Quadruples (Correct answer)
- Halves
Correct answer: Quadruples
Rotational kinetic energy = ½Iω²; doubling ω increases energy by 2² = 4 times.
Question 4: In a belt-and-pulley system, a 10 cm driver pulley turns at 600 RPM driving a 30 cm driven pulley. What is the driven pulley's speed?
- 1800 RPM
- 600 RPM
- 300 RPM
- 200 RPM (Correct answer)
Correct answer: 200 RPM
Pulley speed ratio inversely follows diameter ratio: driven speed = 600 × (10/30) = 200 RPM.
Question 5: A metal beam fixed at one end (cantilever) deflects under a load at its free end. If the load is doubled, the deflection:
- Stays the same
- Doubles (Correct answer)
- Quadruples
- Halves
Correct answer: Doubles
Beam deflection is directly proportional to load for elastic deformation, so doubling the load doubles deflection.
Question 6: What does a manometer measure?
- Electrical resistance
- Fluid pressure (Correct answer)
- Rotational speed
- Tensile strength
Correct answer: Fluid pressure
A manometer measures fluid (liquid or gas) pressure by the height difference of a fluid column.
Question 7: A piston in a cylinder compresses gas from 4 L to 1 L at constant temperature. If the initial pressure was 1 atm, what is the final pressure?
- 0.25 atm
- 1 atm
- 2 atm
- 4 atm (Correct answer)
Correct answer: 4 atm
Boyle's Law: P₁V₁ = P₂V₂; P₂ = (1 atm × 4 L) / 1 L = 4 atm.
GCAT Mechanical Reasoning Concepts 4
A compound pulley system has 4 rope segments supporting a load.
What is the ideal mechanical advantage?