WTMA Mechanical Comprehension 2 — Questions and Answers
Question 1: A lever has its fulcrum positioned 1 foot from a 100-lb load and 4 feet from the effort point. How much force is needed to lift the load?
- 25 lbs (Correct answer)
- 50 lbs
- 100 lbs
- 400 lbs
Correct answer: 25 lbs
Using the lever principle, effort × effort arm = load × load arm, so effort = 100 × 1 ÷ 4 = 25 lbs.
Question 2: Two gears mesh together. Gear A has 20 teeth and turns at 60 RPM. Gear B has 40 teeth. How fast does Gear B turn?
- 120 RPM
- 60 RPM
- 30 RPM (Correct answer)
- 15 RPM
Correct answer: 30 RPM
When gears mesh, speed is inversely proportional to tooth count, so Gear B = 60 × (20/40) = 30 RPM.
Question 3: A hydraulic jack has an input piston with area 2 sq in and output piston with area 10 sq in. If you apply 50 lbs of force to the input, what force does the output produce?
- 10 lbs
- 50 lbs
- 250 lbs (Correct answer)
- 500 lbs
Correct answer: 250 lbs
Pascal's law: output force = input force × (output area ÷ input area) = 50 × (10/2) = 250 lbs.
Question 4: Which type of wrench provides the most torque with the least chance of rounding off a bolt head?
- Open-end wrench
- Adjustable wrench
- Box-end wrench (Correct answer)
- Needle-nose pliers
Correct answer: Box-end wrench
A box-end (closed) wrench grips all six sides of a hex bolt, distributing force evenly and minimizing slippage.
Question 5: A ball is rolling across a flat surface and encounters an incline going downhill. What happens to its speed?
- It slows down
- It stays the same
- It increases (Correct answer)
- It immediately stops
Correct answer: It increases
Gravity adds energy as the ball descends the incline, converting potential energy to kinetic energy and increasing speed.
Question 6: Which of the following materials best conducts heat?
- Wood
- Rubber
- Copper (Correct answer)
- Glass
Correct answer: Copper
Copper is an excellent thermal conductor, commonly used in heat exchangers and cookware for this reason.
Question 7: A fixed pulley at the top of a flagpole is used to raise a flag. What mechanical advantage does it provide?
- It doubles the lifting force
- It triples the lifting force
- It provides no force advantage but changes direction (Correct answer)
- It reduces friction to zero
Correct answer: It provides no force advantage but changes direction
A single fixed pulley has a mechanical advantage of 1 — it changes the direction of force but does not reduce the amount of force needed.
WTMA Mechanical Comprehension 2
A lever has its fulcrum positioned 1 foot from a 100-lb load and 4 feet from the effort point.
How much force is needed to lift the load?