BARB Mechanical Comprehension 1 — Questions and Answers
Question 1: A lever has its fulcrum in the middle. A 10 kg load is placed 2 m to the left. Where must a 5 kg effort be placed on the right to balance it?
- 2 m
- 1 m
- 3 m
- 4 m (Correct answer)
Correct answer: 4 m
Moment = Force × Distance; 10 × 2 = 20 Nm; 5 × d = 20; d = 4 m.
Question 2: Two gears are meshed together. Gear A has 20 teeth and Gear B has 40 teeth. If Gear A turns at 100 rpm, how fast does Gear B turn?
- 200 rpm
- 50 rpm (Correct answer)
- 100 rpm
- 150 rpm
Correct answer: 50 rpm
Gear ratio = 20/40 = 1/2; Gear B turns at 100 × (1/2) = 50 rpm.
Question 3: A pulley system uses two pulleys. What effect does adding a second pulley have?
- It doubles the required effort
- It halves the effort needed to lift a load (Correct answer)
- It has no effect on effort
- It triples the rope length needed
Correct answer: It halves the effort needed to lift a load
A two-pulley system provides a mechanical advantage of 2, halving the effort required.
Question 4: Water flows through a pipe that narrows from 4 cm to 2 cm in diameter. What happens to the water's speed?
- It halves
- It stays the same
- It doubles
- It quadruples (Correct answer)
Correct answer: It quadruples
Cross-sectional area is proportional to diameter squared; halving diameter reduces area by 4×, so speed increases 4×.
Question 5: A soldier uses a ramp to load a heavy crate onto a truck. What mechanical advantage does the ramp provide?
- It increases the distance but reduces the required force (Correct answer)
- It reduces both distance and force
- It increases both distance and force
- It has no mechanical advantage
Correct answer: It increases the distance but reduces the required force
A ramp (inclined plane) reduces the force required by spreading the work over a longer distance.
Question 6: Which of the following is an example of a third-class lever?
- Wheelbarrow
- Crowbar
- Tweezers (Correct answer)
- Seesaw
Correct answer: Tweezers
In tweezers the effort is between the fulcrum and the load, making them a third-class lever.
BARB Mechanical Comprehension 1
A lever has its fulcrum in the middle.
A 10 kg load is placed 2 m to the left.
Where must a 5 kg effort be placed on the right to balance it?