GCAT Mechanical Reasoning Concepts 3 — Questions and Answers
Question 1: A 10 kg object is accelerated at 3 m/s². What net force is acting on it?
- 3.3 N
- 13 N
- 30 N (Correct answer)
- 300 N
Correct answer: 30 N
Newton's second law: F = ma = 10 × 3 = 30 N.
Question 2: Which type of lever has the fulcrum between the effort and the load?
- First-class lever (Correct answer)
- Second-class lever
- Third-class lever
- Fourth-class lever
Correct answer: First-class lever
A first-class lever has the fulcrum between effort and load, like a seesaw or crowbar.
Question 3: A car engine produces 150 kW of power and propels the car at 30 m/s. What is the driving force on the car?
- 5 N
- 500 N
- 5000 N (Correct answer)
- 45,000 N
Correct answer: 5000 N
Power = force × velocity; force = P/v = 150,000 / 30 = 5000 N.
Question 4: A shaft transmits torque from a motor to a wheel. If the shaft's diameter is doubled, by what factor does its torsional strength increase (approximately)?
- 2×
- 4×
- 8×
- 16× (Correct answer)
Correct answer: 16×
Torsional strength scales with the fourth power of diameter; 2⁴ = 16×.
Question 5: Ball bearings are used in rotating machinery primarily to:
- Increase friction to slow rotation
- Reduce friction and support radial loads (Correct answer)
- Increase torque output
- Convert rotational to linear motion
Correct answer: Reduce friction and support radial loads
Ball bearings replace sliding friction with rolling friction, greatly reducing energy loss while supporting loads.
Question 6: A screw has a pitch of 2 mm. How many full turns are needed to advance the screw 10 mm into a surface?
- 2 turns
- 5 turns (Correct answer)
- 10 turns
- 20 turns
Correct answer: 5 turns
Turns = distance / pitch = 10 mm / 2 mm = 5 turns.
Question 7: An object moving in a circle at constant speed is experiencing a net force directed:
- Outward from the center
- Tangent to the circle
- Toward the center (Correct answer)
- Opposite to motion
Correct answer: Toward the center
Centripetal force always points toward the center of the circle, causing the object to follow a curved path.
GCAT Mechanical Reasoning Concepts 3
A 10 kg object is accelerated at 3 m/s².
What net force is acting on it?