Mechanical Aptitude Flashcards
7 cards from real NFST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Mechanical Aptitude flashcards as text
A centrifugal pump is running but delivering no water. Which of the following is the most likely cause?
Answer: The pump is air-locked (not primed)
Centrifugal pumps cannot pump air; if not primed with water, they spin without moving fluid, a condition called air-lock or vapor lock.
On a fire apparatus, what is the purpose of a pressure governor?
Answer: To maintain a preset discharge pressure automatically
A pressure governor automatically adjusts engine throttle to maintain a steady, preset discharge pressure despite changes in demand.
A wrench handle is 12 inches long and 30 lbs of force is applied. What is the torque applied to the bolt?
Answer: 30 ft-lbs
Torque = Force × Distance = 30 lbs × 1 ft (12 inches) = 30 ft-lbs.
Which of the following materials has the highest thermal conductivity and would transfer heat most rapidly?
Answer: Copper
Copper is an excellent thermal conductor and transfers heat far more rapidly than wood, fiberglass, or rubber.
A spring scale reads 50 lbs when an object is weighed in air, but only 40 lbs when submerged in water. What is the buoyant force acting on the object?
Answer: 10 lbs
Buoyant force equals the difference between the weight in air and the apparent weight in water: 50 - 40 = 10 lbs.
When two gears mesh together, in which direction does the driven gear rotate relative to the driver gear?
Answer: The opposite direction
When two gears mesh directly, they always rotate in opposite directions; an idler gear is needed to make them rotate in the same direction.
What is the primary purpose of a check valve in a fire hose or pump system?
Answer: To allow flow in one direction only
A check valve permits fluid to flow in one direction only, preventing backflow that could contaminate the water supply or damage equipment.