ADF ADF Mechanical Reasoning 1 — Questions and Answers
Question 1: Gear A has 20 teeth and meshes with Gear B which has 10 teeth. If Gear A completes one full rotation, how many rotations does Gear B complete?
- Half a rotation
- One rotation
- Two rotations (Correct answer)
- Four rotations
Correct answer: Two rotations
Gear ratio equals the driver's tooth count divided by the driven gear's; 20 ÷ 10 = 2, so Gear B completes two rotations for every one rotation of Gear A.
Question 2: Which class of lever has the effort force applied between the fulcrum and the load?
- First-class lever
- Second-class lever
- Third-class lever (Correct answer)
- Fourth-class lever
Correct answer: Third-class lever
A third-class lever places the effort between the fulcrum and the load; tweezers and a fishing rod are common examples.
Question 3: A system uses one fixed pulley and one movable pulley. By what factor does this reduce the force needed to lift a load?
- Force is unchanged
- Force is reduced by half (Correct answer)
- Force is reduced by one quarter
- Force is doubled
Correct answer: Force is reduced by half
A compound pulley with one fixed and one movable pulley gives a mechanical advantage of 2, halving the required effort force.
Question 4: Water flows through a pipe that suddenly narrows. What happens to the water's velocity in the narrower section?
- Velocity decreases
- Velocity increases (Correct answer)
- Velocity stays the same
- Flow stops
Correct answer: Velocity increases
The continuity principle states that for an incompressible fluid, flow rate is constant, so velocity must increase when the cross-sectional area decreases.
Question 5: Of the following materials, which is the best conductor of electricity?
- Rubber
- Glass
- Copper (Correct answer)
- Wood
Correct answer: Copper
Copper has very low electrical resistance and abundant free electrons, making it the standard material for electrical wiring.
Question 6: What mechanical advantage does a wedge provide?
- It reduces the work done on the load
- It multiplies the applied force over a shorter distance (Correct answer)
- It only changes the direction of force without multiplying it
- It increases friction to hold objects in place
Correct answer: It multiplies the applied force over a shorter distance
A wedge converts a smaller force applied over a longer distance into a larger force acting over a shorter distance, effectively multiplying the input force.
ADF ADF Mechanical Reasoning 1
Gear A has 20 teeth and meshes with Gear B which has 10 teeth.
If Gear A completes one full rotation, how many rotations does Gear B complete?