GCAT Mechanical Reasoning Concepts 5 ā Questions and Answers
Question 1: A cam converts:
- Rotational motion to linear (reciprocating) motion (Correct answer)
- Linear motion to rotational motion
- High torque to low speed
- Electrical energy to mechanical energy
Correct answer: Rotational motion to linear (reciprocating) motion
A cam is a rotating or sliding piece that pushes a follower up and down, converting rotation to reciprocating motion.
Question 2: Which of the following best describes mechanical advantage?
- The speed at which a machine operates
- The ratio of output force to input force (Correct answer)
- The ratio of input force to output force
- The total energy a machine produces
Correct answer: The ratio of output force to input force
Mechanical advantage = output force / input force, indicating how much a machine multiplies applied force.
Question 3: A steel I-beam is used in construction because compared to a solid rectangular beam of the same weight, it has:
- Less bending resistance
- Greater bending resistance (Correct answer)
- Less compressive strength
- The same bending resistance
Correct answer: Greater bending resistance
The I-shape places material far from the neutral axis, maximizing the second moment of area and bending resistance.
Question 4: A 5 kg object falls freely for 3 seconds (g = 10 m/sĀ²). What is its velocity just before impact?
- 15 m/s
- 30 m/s (Correct answer)
- 45 m/s
- 150 m/s
Correct answer: 30 m/s
v = gt = 10 Ć 3 = 30 m/s (mass is irrelevant to free-fall velocity).
Question 5: A worm gear drive has a worm with 1 thread meshing a 50-tooth worm wheel. What is the gear ratio?
- 1:1
- 1:50
- 50:1 (Correct answer)
- 25:1
Correct answer: 50:1
A single-thread worm advances the wheel by one tooth per revolution, giving a 50:1 speed reduction ratio.
Question 6: Which type of stress occurs when forces pull a material apart along its length?
- Compressive stress
- Shear stress
- Torsional stress
- Tensile stress (Correct answer)
Correct answer: Tensile stress
Tensile stress results from forces pulling a material in opposite directions along its axis, stretching it.
Question 7: A tank of water has an outlet pipe at the bottom. The flow rate through the pipe depends primarily on:
- The color of the tank
- The total volume of water in the tank
- The height of water above the outlet (Correct answer)
- The width of the tank
Correct answer: The height of water above the outlet
Flow rate from a tank outlet depends on the head pressure, which is determined by the height of fluid above the outlet.
